Summary:
This diff revises how to handle the unknown location in inferbo in two ways:
* stop appending field to the `Unknown` location, e.g. `Unknown.x.a` is evaluated to `Unknown`
* redesign the abstract of multiple locations, like `Bottom` < `Unknown` < `Known` locations
I am doing them in one diff since applying only one of them showed bad results.
Background: `Unknown` was adopted for abstracting all unknown concrete locations, so we could avoid missing semantics of assignments to unknown locations. We tried to keep soundness. However, it brought some other problems related to precision and performance.
1. Sometimes especially when Inferbo failed to reason precise pointer values, `Unknown` may point to many other abstract locations.
2. At that time, value assignments to `*Unknown` makes the situation worse: many abstract locations are updated with imprecise values.
This problem harmed not only its precision, but also its performance since it introduced more location entries in the abstract memory.
Reviewed By: jvillard
Differential Revision: D21017789
fbshipit-source-id: 0bb6bd8b5
Summary:
As soon as pulse detects an error, it completely stops the analysis and loses the state where the error occurred. This makes it difficult to debug and understand the state the program failed. Moreover, other analyses that might build on pulse (e.g. impurity), cannot access the error state.
This diff aims to restore and display the state at the time of the error in `PulseExecutionState` along with the diagnostic by extending it as follows:
```
type exec_state =
| represents the state at the program point that caused an error *)
```
As a result, since we don't immediately stop the analysis as soon as we find an error, we detect both errors in conditional branches simultaneously (see test result changes for examples).
NOTE: We need to extend `PulseOperations.access_result` to keep track of the failed state as follows:
```
type 'a access_result = ('a, Diagnostic.t * t [denoting the exit state] ) result
```
Reviewed By: jvillard
Differential Revision: D20918920
fbshipit-source-id: 432ac68d6
Summary: Consider functions that simply exit as impure by extending the impurity domain with `AbstractDomain.BooleanOr` that signifies whether the program exited.
Reviewed By: skcho
Differential Revision: D20941628
fbshipit-source-id: 19bc90e66
Summary:
This diff distinguishes array declaration and size-setting in trace. For example, when there is an
assume statement on an array size, the array size can be pruned to another value. In which case, we
want to see "Set array size" in the trace, instead of "Array declaration".
Reviewed By: jvillard
Differential Revision: D20914930
fbshipit-source-id: 0253fb69e
Summary:
This diff lifts the `PulseAbductiveDomain.t` in `PulseExecutionState` by tracking whether the program continues the analysis normally or exits unusually (e.g. by calling `exit` or `throw`):
```
type exec_state =
| ContinueProgram of PulseAbductiveDomain.t (** represents the state at the program point *)
| ExitProgram of PulseAbductiveDomain.t
(** represents the state originating at exit/divergence. *)
```
Now, Pulse's actual domain is tracked by `PulseExecutionState` and as soon as we try to analyze an instruction at `ExitProgram`, we simply return its state.
The aim is to recover the state at the time of the exit, rather than simply ignoring them (i.e. returning empty disjuncts). This allows us to get rid of some FNs that we were not able to detect before. Moreover, it also allows the impurity analysis to be more precise since we will know how the state changed up to exit.
TODO:
- Impurity analysis needs to be improved to consider functions that simply exit as impure.
- The next goal is to handle error state similarly so that when pulse finds an error, we recover the state at the error location (and potentially continue to analyze?).
Disclaimer: currently, we handle throw statements like exit (as was the case before). However, this is not correct. Ideally, control flow from throw nodes follows catch nodes rather than exiting the program entirely.
Reviewed By: jvillard
Differential Revision: D20791747
fbshipit-source-id: df9e5445a
Summary:
It's easy to create large arrays in code, eg `int x[1UL << 16];`, but
these can generate huge nodes in SIL because zero-initialization is
translated by zero-ing structures element by element. Introduce a
builtin to use instead. Keep the naive method for small structures (with
a configurable limit on "small").
Reviewed By: dulmarod
Differential Revision: D20836836
fbshipit-source-id: 6bf5410f8
Summary:
- Add `no_return` models for Java's `exit(...)` methods (can be extended further later on)
- handle throw-catch better by short-cutting throw nodes to not exit node but to all **catch nodes** that are reachable by the node. If there is no catch node, we short-cut to the exit node as before.
This removes a FP from deadstore tests because before we simply were not able to handle CF from throw-> catch nodes at all.
Reviewed By: skcho
Differential Revision: D20769039
fbshipit-source-id: e978f6cdb
Summary: In an intra-procedural analysis we assume that parameters passed by reference to a function will be initialized inside that function. We use the type information of an actual parameter to initialize the fields of the struct. This does not work if a function has a parameter of type void* as the actual parameters also has type void*. To solve this issue, we use type information from local variables.
Reviewed By: jvillard
Differential Revision: D20670253
fbshipit-source-id: dc9f051ef
Summary:
- Model `System.exit()` as early_exit and add a test
- Tweak message of methods that are impure due to having no pulse summary (and add a test)
Reviewed By: skcho
Differential Revision: D20668979
fbshipit-source-id: 6b5589aae
Summary:
Hopefully no one uses this. This is in Python and we'd like to get rid
of it. Easy enough to either re-implement if needed or to be
re-implemented by a third party.
Reviewed By: ngorogiannis
Differential Revision: D20626344
fbshipit-source-id: 484022482
Summary:
As exemplified by added tests, pulse computes an empty summary (with 0 disjuncts) whenever it discovers a contradiction which might be caused by:
- discovering aliasing in memory
- widening limited number of times in loops and concluding that loop exit conditions are never taken
However, AFAIU, it is not possible to have a function with 0 disjunct apart from such anomalities. Even a function which does nothing like `void foo(){}` has 1 disjuncts:
```
Pulse: 1 pre/post(s)
#0: PRE:
{ roots={ };
mem ={ };
attrs={ };}
POST:
{ roots={ };
mem ={ };
attrs={ };}
SKIPPED_CALLS: { }
```
The aim of this diff is to consider functions with 0 disjuncts as **impure** because most often such cases are impure, rather than actually pure.
Reviewed By: skcho
Differential Revision: D20619504
fbshipit-source-id: 3a8502c90
Summary:
Previously, at each function call, we added a `WrittenTo` attribute for applying the address of the actuals. However, this results in mistakenly considering each function application that inspects its argument as impure. Instead, we should only propagate `WrittenTo` if the actuals have already `WrittenTo` attributes.
For instance, for the following functions
```
public static boolean is_null(Byte a) {
return a == null;
}
public static boolean call_is_null(Byte a) {
return is_null(a);
}
```
We used to get the following pulse summary for `call_is_null` (showing only one of the disjuncts):
```
#0: PRE:
{ roots={ &a=v1 };
mem ={ v1 -> { * -> v2 } };
attrs={ v1 -> { MustBeValid },
v2 -> { Arith =null, BoItv ([max(0, v2), min(0, v2)]) } };}
POST:
{ roots={ &a=v1, &return=v8 };
mem ={ v1 -> { * -> v2 }, v8 -> { * -> v4 } };
attrs={ v2 -> { Arith =null,
BoItv ([max(0, v2), min(0, v2)]),
WrittenTo-----------WRONG },
v4 -> { Arith =1,
BoItv (1),
Invalid ConstantDereference(is the constant 1),
WrittenTo-----------WRONG },
v8 -> { WrittenTo } };}
SKIPPED_CALLS: { }
```
where we mistakenly recorded a `WrittenTo` for `v2` (what `a` points to). As a result, we considered `call_is_null` as impure :( This diff fixes that since the callee `is_null` doesn't have any `WrittenTo` attributes for its parameter `a`. So, we don't propagate `WrittenTo` and get the following summary
```
#0: PRE:
{ roots={ &a=v1 };
mem ={ v1 -> { * -> v2 } };
attrs={ v1 -> { MustBeValid },
v2 -> { Arith =null, BoItv ([max(0, v2), min(0, v2)]) } };}
POST:
{ roots={ &a=v1, &return=v8 };
mem ={ v1 -> { * -> v2 }, v8 -> { * -> v4 } };
attrs={ v2 -> { Arith =null, BoItv ([max(0, v2), min(0, v2)]) },
v4 -> { Arith =1,
BoItv (1),
Invalid ConstantDereference(is the constant 1) },
v8 -> { WrittenTo } };}
SKIPPED_CALLS: { }
```
Reviewed By: skcho
Differential Revision: D20490102
fbshipit-source-id: 253d8ef64
Summary: There has never been a sufficient formal basis for soundness nor completeness of reports on locals. This diff changes the domain to effectively concern only expressions rooted at formals or globals.
Reviewed By: ezgicicek
Differential Revision: D19769201
fbshipit-source-id: 36ae04d8c
Summary:
Impurity domain was tracking all changes to variables (with a list of traces that containing all write/invalid accesses). This results in having long traces with multiple access events for the same variable. For instance,
```
void swap_impure(int[] array, int i, int j) {
int tmp = array[i];
array[i] = array[j]; \\ included in the trace
array[j] = tmp; \\ included in the trace
}
```
here we recorded both array accesses.
This diff changes the domain to include accesses so that we only keep track of a single trace per access. Array accesses are only recorded once.
Note that we want to record all unique accesses, not just the first one, because impurity will be used for hoisting/cost where we will invalidate impure arguments and consider all the rest as not changing.
Reviewed By: jvillard
Differential Revision: D20385745
fbshipit-source-id: d3647dad3
Summary:
D20362149 missed
- to pass the optional argument `include_value_history` to the recursive call in `PulseTrace.add_to_errlog`.
- to set `include_value_history=false` for skipped calls.
This diff fixes these issues.
Reviewed By: skcho
Differential Revision: D20385604
fbshipit-source-id: 176e4d010
Summary:
This was never quite finished and inferbo has a new way to do sort of
the same thing.
Reviewed By: skcho, ngorogiannis
Differential Revision: D20362619
fbshipit-source-id: 7c7935d47
Summary: Impurity traces are quite big due to recording values histories. Let's simplify the traces by removing pulse's value histories.
Reviewed By: skcho
Differential Revision: D20362149
fbshipit-source-id: 8a2a6115e
Summary:
These were not used (and were actually activated byt the same config
param). They both are in experimental stage that never reached maturity.
Since the team does not have immediate plans to work on ObjC nullability
checker; and since "eradicate" (now known as nullsafe) is the main
solution for Java, removing it is sensible.
Reviewed By: jvillard
Differential Revision: D20279866
fbshipit-source-id: 79e64992b
Summary: This diff suppresses integer overflow issues in functions that includes "hash" in its name.
Reviewed By: jvillard
Differential Revision: D19942654
fbshipit-source-id: d86fa4f00
Summary:
When finding a proper constructor for `std::make_shared`, the given parameter types are sometimes
slightly different, e.g., const int vs int. This diff loosens the condition of the types on finding
constructors.
Reviewed By: ngorogiannis
Differential Revision: D19743198
fbshipit-source-id: f90213109
Summary:
This diff fixes the clang translation for switch statement. It assumed that `default:` comes always
at last, which introduced some unreachable nodes inadvertently, e.g. when `default:` comes at first.
Reviewed By: dulmarod
Differential Revision: D19793138
fbshipit-source-id: 1e8b52c0d
Summary:
The goals are:
- Increase precision in C-languages by ditching access paths.
- Help with eventually sharing the abstract address module with RacerD.
- Reports are now language-mode specific (eg `->` in clang vs `.` in Java).
It's not exactly access expressions used here. Instead the pattern `(base, access list)` is used where `access` is `HilExp.Access.t`. This is done to ease the way `deriving` is used for creating two comparison functions, one that cares about the root variable and one that doesn't; and also because the main function that recurses over accesses (`normalise_access_list`) visits the accesses from innermost to outermost.
Also, kill some dead code.
Reviewed By: skcho
Differential Revision: D19741545
fbshipit-source-id: 013bf1a89
Summary:
This diff adds a taint domain in Inferbo. The taint value will be used to find vulnerable array
accesses in the following diffs.
Reviewed By: ezgicicek
Differential Revision: D19391028
fbshipit-source-id: 566b4c0fe
Summary:
To emulate the `ThreadSafe` contract in C++/ObjC, reporting was gated behind a check that ensured a C++/ObjC class has a `std::mutex` member (plus other filters). This is reasonable, but it has some drawbacks
- other locks may be used, and therefore must be added to the member check;
- locking mechanisms that use the object itself as a monitor cannot be modelled (`synchronized` in ObjC)
RacerD already has `ThreadsDomain` which models our guess on whether a method is expected to run in a concurrent context, and which in C++/ObjC boils down to whether the method non-transitively acquires a lock. This should be a good enough indicator that the class should be checked regardless of whether the locks are member fields. This diff gates the C++/ObjC check on that abstract property.
Reviewed By: dulmarod
Differential Revision: D19558355
fbshipit-source-id: 229d7ff82
Summary: This diff fixes the array access checking function for nested global arrays. We had assumed that RHS of `store` statement in SIL does not include array access expression, but that is not true: for global arrays, SIL can have statements like `*LHS = GlobalArray[n][m]`.
Reviewed By: ezgicicek
Differential Revision: D19300153
fbshipit-source-id: 256325642
Summary:
This diff gives semantics of `std::make_shared` as simple constructor, i.e., it changes function
call of `std::make_chared<C>(i)` to the constructor `C(i)`.
Reviewed By: ngorogiannis
Differential Revision: D19432338
fbshipit-source-id: 0d838e555
Summary:
This diff gets global constant array values from their initializers. The `find_global_array` function is
added to memory domain, which finds values of global array locations during the ondemand value
generation.
Reviewed By: ngorogiannis
Differential Revision: D19300143
fbshipit-source-id: 7b0b84c42
Summary:
If a race exists in two or more overloads of the same method and we use only the class and method name in the report text, then the current bug hashing algorithm will identify the two reports as duplicates.
To avoid this, the report had the class, method and list of type parameters. This is unreadable, however, and redundant (the report is already located within the method in question). So at the risk of duplicates, use only class+method names.
Also, fix a bug in `Procname.pp_simplified ~withclass` where `withclass` was ignored for C++/ObjC methods.
Now:
> Read/Write race. Non-private method `FrescoVitoImageSpec.onCreateInitialState(...)` indirectly reads with synchronization from `factory.AnimatedFactoryProvider.sImpl`. Potentially races with unsynchronized write in method `FrescoVitoImageSpec.onEnteredWorkingRange(...)`.@ [Litho components are required to be thread safe because of multi-threaded layout](https://fburl.com/background-layout). Reporting because current class is annotated `MountSpec`, so we assume that this method can run in parallel with other non-private methods in the class (including itself).
Before
> Read/Write race. Non-private method `void FrescoVitoImageSpec.onCreateInitialState(ComponentContext,StateValue,StateValue,Uri,MultiUri,ImageOptions,FrescoContext,Object,ImageListener)` indirectly reads with synchronization from `factory.AnimatedFactoryProvider.sImpl`. Potentially races with unsynchronized write in method `FrescoVitoImageSpec.onEnteredWorkingRange(...)`.@ [Litho components are required to be thread safe because of multi-threaded layout](https://fburl.com/background-layout). Reporting because current class is annotated `MountSpec`, so we assume that this method can run in parallel with other non-private methods in the class (including itself).
Reviewed By: artempyanykh
Differential Revision: D19462277
fbshipit-source-id: aebc20d89
Summary:
Currently, impurity analysis is oblivious to skipped functions which might e.g. return a non-deterministic value, write to memory or have some other side-effect. This diff fixes that by relying on Pulse's skipped functions to determine impurity. Any unknown function which is not modeled to be pure is assumed to be impure.
This is a heuristic. We could have assumed them to be pure by default as well.
Reviewed By: jvillard
Differential Revision: D19428514
fbshipit-source-id: 82efe04f9
Summary: This diff captures global initializers ondemand, like we do for functions defined in headers.
Reviewed By: ezgicicek
Differential Revision: D19346947
fbshipit-source-id: 05174e6a4
Summary:
Demonstrate that the per-file type environments don't prevent
the deadlock report here. The fear was that when the analyser
tries to locate the methods of the endpoint class, it might fail to
do so because the types might be stored in different type
environments (per file).
Reviewed By: mityal
Differential Revision: D19225908
fbshipit-source-id: 097e4aeea
Summary:
A plus is a plus, no need to give up when +/- is about pointers. This
gets rid of some false positives involving pointer arithmetic.
However, the problem remains if we make things a bit more
inter-procedural. This is documented in an added test.
Reviewed By: ezgicicek
Differential Revision: D18932877
fbshipit-source-id: 4ad1cfe72
Summary:
The `Typ.FIeldname` module has many issues. Among those:
- It has 5 different string/printing functions and most of them do radically different things in Java and in Clang.
- There is no type safety: creating a Clang field and calling a Java function on it will lead to a crash (`rindex_exn` etc, there are usually no dots in Clang fields).
- It uses a single string for Java fields, containing the package, the class and the field, e.g., `java.lang.Object.field`. This is wasteful, because
- there is no sharing of strings for packages/classes, and,
- string operations need to be performed every time we need the field or the class or the package alone.
This diff preserves the behaviour of the module's interface, so the API problems remain.
However, by using a saner representation for Java fields we can get small performance and large memory gains (the type environment in Java is much smaller, about 30-40%).
In addition, many functions on clang fields would previously do string manipulations (look for `.` and split on it) before returning the final field unchanged -- now they use the type of the field for that.
Reviewed By: jvillard
Differential Revision: D18908864
fbshipit-source-id: a72d847cc
Summary:
- Do most of the work of `solve_arithmetic_constraints` inside `subst_attribute` instead, since we need to re-use the latter function for post-conditions where the first function is not appropriate.
- When substituting arithmetic constraints, we refine arithmetic information (both concrete intervals and inferbo), which can lead to inconsistent states. Instead of recording the new arithmetic facts by returning a new current state, just act as a map on attributes. This is to enable doing the point above.
- All this lead to a somewhat messy refactoring...
- Rename `CannotApplyPre` to `Contradiction` since it's used for post-conditions as well now
Reviewed By: skcho
Differential Revision: D18889120
fbshipit-source-id: d81647143
Summary:
Pointers are hard... The previous test had no chance of doing
initialisation of the pointer by reference and was in fact a false
negative (and still is, fix incoming). Renamed functions to stress the
false negative and added a test that is really (potentially) doing
pointer initialisation by reference.
Reviewed By: skcho
Differential Revision: D18888008
fbshipit-source-id: 1e72408c7
Summary:
Finally use information from the inferbo intervals in pulse's domain to
make decisions about whether conditionals are feasible or not.
Reviewed By: skcho
Differential Revision: D18811193
fbshipit-source-id: d80a28657
Summary: This diff extends the bound domain to express multiplication of bounds in some simple cases.
Reviewed By: ezgicicek
Differential Revision: D18745246
fbshipit-source-id: 4f2dcb42c
Summary:
This gets rid of false positives when something invalid (eg null) is
passed by reference to an initialisation function. Havoc'ing what the
contents of the pointer to results in being optimistic about said
contents in the future.
Also surprisingly gets rid of some FNs (which means it can also
introduce FPs) in the `std::atomic` tests because a path condition
becomes feasible with havoc'ing.
There's a slight refinement possible where we don't havoc pointers to
const but that's more involved and left as future work.
Reviewed By: skcho
Differential Revision: D18726203
fbshipit-source-id: 264b5daeb
Summary:
It's a well-known fact that pulse should know too. To avoid splitting
the abstract state systematically, only act if we know the pointer is
exactly 0 to avoid reporting a nullptr dereference on `free(x)`.
Reviewed By: ezgicicek
Differential Revision: D18708575
fbshipit-source-id: 1cc3f6908
Summary:
Turns out code uses atomics in important places, modelling it removes
FPs.
The tests are copied from biabduction and adapted and extended a bit. I
didn't implement compare_exchange primitives for now (plus, giving them
a sequential semantics like in biabduction is probably a bit cheeky).
Reviewed By: skcho
Differential Revision: D18708576
fbshipit-source-id: a3581b8a4
Summary:
This diff adds inferbo's interval values to pulse's attributes. The added values will be used to
filter out infeasible passes in the following diffs.
Reviewed By: jvillard
Differential Revision: D18726667
fbshipit-source-id: c1125ac6e
Summary:
A plugin update allows infer to know when a function doesn't return
according to its attributes. This propagates this info all the way to
the attributes of each function, and then use this information in a new
pre-analysis that cuts the links to successor nodes of each `Call`
instruction to a function that does not return.
NOTE: The "no_return" `CallFlag.t` was dead code, following diffs deal
with that (by removing it).
Reviewed By: dulmarod
Differential Revision: D18573922
fbshipit-source-id: 85ec64eca
Summary:
This also prints the CFGs *after* pre-analysis for individual procedures
in infer-out/captured/<filename>/<proc>.dot. One can also look up the
CFGs before pre-analysis in infer-out/captured/proc_cfgs_frontend.dot.
Context: I want to add a pre-analysis that needs to look at proc
attributes inter-procedurally. For this to make sense it has to happen
*after* all of capture, and before analysis.
Thus, this diff brings back the lazy running of the pre-analysis like in
D15803492, except that we still make sure to run the pre-analyses
systematically regardless of the checkers being run by running the
pre-analysis from ondemand.ml. Also we don't need to re-introduce the
"did_preanalysis" proc attribute for the same reason that the
pre-analysis is now run once and for all by ondemand.ml (instead of each
individual checker back in the days).
This has the benefit of running the pre-analysis only when needed, and
the drawback that several concurrent processes analysing the same proc
descs will duplicate work. Since pre-analyses are supposed to be very
fast I assume that neither is a big deal. If they become more expensive
then the benefit gets bigger and the drawback is just the same as with
regular analyses.
Reviewed By: skcho
Differential Revision: D18573920
fbshipit-source-id: de350eaef
Summary:
- more flexible API
- less error-prone thanks to named parameters
- also takes care of adjusting predecessors of the previous successors!
This fixes some (probably harmless) bugs in the frontends.
Reviewed By: dulmarod
Differential Revision: D18573923
fbshipit-source-id: ad97b3607
Summary:
Note: Disabled by default.
Having some support for values, we can report when a null or constant
value is being dereferenced. The particularity here is that we don't
report when 0 is a possible value for the address, or even if we know
that the value of the address can only be 0 in that branch! Instead, we
allow ourselves to report only when we the address has been *set* to
NULL (or any constant).
This is in line with how pulse deals with other issues: only report when
1. we see an address become invalid, and
2. we see the same address be used later on
Reviewed By: skcho
Differential Revision: D17665468
fbshipit-source-id: f1ccf94cf
Summary:
This adds a more interesting value domain to pulse: concrete intervals.
There are still two main limitations:
1. arithmetic operations are all over-approximated: any assignment involving arithmetic operations is replaced by non-determinism
2. abstract values that are discovered to be equal are not merged into one
Reviewed By: skcho
Differential Revision: D18058972
fbshipit-source-id: 0492a590f
Summary:
This does several things because it was hard to split it more:
1. Split most of the arithmetic reasoning to PulseArithmetic.ml. This
doesn't need to be reviewed thoroughly because an upcoming diff
changes the domain from just `EqualTo of Const.t` to an interval domain!
2. When going through a prune node intra-procedurally, abduce arithmetic
facts to the pre (instead of just propagating them). This is the "assume
as assert" trick used by biabduction 1.0 too and allows to propagate
arithmetic constraints to callers.
3. Use 2 when applying summaries by pruning specs whose preconditions
have un-satisfiable arithmetic constraints.
This changes one of the tests! Pulse now does a bit more work to find
the false positive, as can be seen in the longer trace.
Reviewed By: skcho
Differential Revision: D18117160
fbshipit-source-id: af3b2c8c0
Summary:
Previously, we considered a function which modifies its parameters to be impure even though it might not be modifying the underlying value. This resulted in FPs like the following program in Java:
```
void fresh_pure(int[] a) {
a = new int[1];
}
```
Similarly, in C++, we considered the following program as impure because it was writing to `s`:
```
Simple* reassign_pure(Simple* s) {
s = new Simple{2};
return s;
}
```
This diff fixes that issue by starting the check for address equivalnce in pre-post not directly from the addresses of the stack variables, but from the addresses pointed to by these stack variables. That means, we only consider things to be impure if the actual values pointed by the parameters change.
Reviewed By: skcho
Differential Revision: D18113846
fbshipit-source-id: 3d7c712f3
Summary: In preparation for improvements to the arithmetic reasoning.
Reviewed By: dulmarod
Differential Revision: D17977207
fbshipit-source-id: ee98e0772
Summary:
bigmacro_bender
There are 3 ways pulse tracks history. This is at least one too many. So
far, we have:
1. "histories": a humble list of "events" like "assigned here", "returned from call", ...
2. "interproc actions": a structured nesting of calls with a final "action", eg "f calls g calls h which does blah"
3. "traces", which combine one history with one interproc action
This diff gets rid of interproc actions and makes histories include
"nested" callee histories too. This allows pulse to track and display
how a value got assigned across function calls.
Traces are now more powerful and interleave histories and interproc
actions. This allows pulse to track how a value is fed into an action,
for instance performed in callee, which itself creates some more
(potentially now interprocedural) history before going to the next step
of the action (either another call or the action itself).
This gives much better traces, and some examples are added to showcase
this.
There are a lot of changes when applying summaries to keep track of
histories more accurately than was done before, but also a few
simplifications that give additional evidence that this is the right
concept.
Reviewed By: skcho
Differential Revision: D17908942
fbshipit-source-id: 3b62eaf78
Summary:
- add the variable being declared so we can report it back in the trace in addition to its location
- distinguish between local vars and formals
Reviewed By: skcho
Differential Revision: D17930348
fbshipit-source-id: a5b863e64
Summary:
Instead of a string argument named `~str` pass `Formal | Global` and let
`add_to_errlog` figure out how to print it.
Reviewed By: ezgicicek
Differential Revision: D17907657
fbshipit-source-id: ed09aab72
Summary:
When we make the decision to go into a branch "v = N" where some
abstract value is compared to a constant, remember the corresponding
equality. This allows to prune simple infeasible paths
intra-procedurally.
Further work is needed to make this useful interprocedurally, for
instance either or both of these ideas could be explored:
- abduce v=N in the precondition and do not apply summaries when the
equalities in the pre are not satisfied
- prune post-conditions that lead to unsat states where a value has to
be equal to several different constants
Reviewed By: skcho
Differential Revision: D17906166
fbshipit-source-id: 5cc84abc2
Summary:
When we know "x = 3" and we have a condition "x != 3" we know we can
prune the corresponding path.
Reviewed By: skcho
Differential Revision: D17665472
fbshipit-source-id: 988958ea6
Summary: If we have no pulse summary (most likely caused by pulse finding a legit issue with the code), let's consider the function as impure.
Reviewed By: jvillard
Differential Revision: D17906016
fbshipit-source-id: 671d3e0ba
Summary:
Previously deduplication was always on which is not great for testing.
Also split tests so that we can still test deduplication separately.
Reviewed By: mityal
Differential Revision: D17686877
fbshipit-source-id: 280d91473
Summary:
Unfortunately it is very hard to predict when
`Typ.Procname.describe` will add `()` after the function name, so we
cannot make sure it is always there.
Right now we report clowny stuff like "error while calling `foo()()`",
which this change fixes.
Reviewed By: ezgicicek
Differential Revision: D17665470
fbshipit-source-id: ef290d9c0
Summary:
Introduce a new experimental checker (`--impurity`) that detects
impurity information, tracking which parameters and global variables
of a function are modified. The checker relies on Pulse to detect how
the state changes: it traverses the pre and post pairs starting from
the parameter/global variable and finds where the pre and post heaps
diverge. At diversion points, we expect to see WrittenTo/Invalid attributes
containing a trace of how the address was modified. We use these to
construct the trace of impurity.
This checker is a complement to the purity checker that exists mainly
for Java (and used for cost and loop-hoisting analyses). The aim of
this new experimental checker is to rely on Pulse's precise
memory treatment and come up with a more precise im(purity)
analysis. To distinguish the two checkers, we introduce a new issue
type `IMPURE_FUNCTION` that reports when a function is impure, rather
than when it is pure (as in the purity checker).
TODO:
- improve the analysis to rely on impurity information of external
library calls. Currently, all library calls are assumed to be nops,
hence pure.
- de-entangle Pulse reporting from analysis.
Reviewed By: skcho
Differential Revision: D17051567
fbshipit-source-id: 5e10afb4f
Summary: Use_after_free was used both for biabduction and pulse, and the biabduction version is blacklisted by default. As a result, the Pulse version was also disabled unintentionally. This changes the name of the old use_after_free so that now we can get use_after_free bugs whenever pulse is enabled.
Reviewed By: skcho
Differential Revision: D17182687
fbshipit-source-id: 539ca69de
Summary: With this predicate we are able to check for static global variables in AL.
Reviewed By: ddino
Differential Revision: D17164848
fbshipit-source-id: a3d10598c
Summary:
This diff uses the models of vector for modelling string in Cpp.
Depends on D16963153
Reviewed By: ezgicicek
Differential Revision: D16963166
fbshipit-source-id: 5effe2d72
Summary:
This is more powerful than `"symbols"` for more advanced use-cases. Keep
`"symbols"` unchanged to make migrating easier.
Differential Revision: D16985756
fbshipit-source-id: dfbb09393
Summary: Adding new predicate for checking whether a variable is defined as extern. May be useful in AL rules.
Reviewed By: jvillard
Differential Revision: D16961690
fbshipit-source-id: 0677077dc
Summary:
Use whatever information we can to decide whether to use C or Java
syntax when outputting an access expression, now that we store them as
such.
Also, make cluster callbacks explicitly set the language, as this was not done before and led to some confusion (Clang being set when analysing a Java file).
Reviewed By: skcho
Differential Revision: D16884160
fbshipit-source-id: 40adf9f35
Summary:
Change the logic of the annotation reachability checker in the following
ways:
1. Sanitizers take priority over sinks, i.e. a procedure that is both a
sink and a sanitizer is not a sink. This changes the existing tests
that seemed to assume the opposite. However I think that way is more
useful and goes better with the fact that sanitizers are specified as
"overrides".
2. When applying a summary, check again that we are not in a sanitizer
for the corresponding sink.
Without (2) this there was a subtle bug when several rules were
specified. For example, if `sink_wrapper()` wraps `sink()` for a rule
`R` then the summary of `sink_wrapper()` will be: `R-sink : call to sink()`.
Then, suppose `sanitizer()` calls `sink_wrapper()` and `sanitizer()` is
a sanitizer for `R` but not for another rule `R'`. The previous code
would add the call to `sink()` to the summary of `sanitizer()` because
it's not a sanitizer for `R'`, even though `sink()` is not a sink for
`R'`!
The current code will re-apply the rules correctly so that sinks are
matched only against the right sanitizers.
Reviewed By: skcho
Differential Revision: D16895577
fbshipit-source-id: 266cc4940
Summary:
- run the tests! they weren't hooked up to the main Makefile :/
- add some html debug messages
- formatting
Reviewed By: skcho
Differential Revision: D16895578
fbshipit-source-id: e96d737cc
Summary:
It adds a vector model of `data` method.
Depends on D16687280
Reviewed By: ezgicicek
Differential Revision: D16689400
fbshipit-source-id: 156016b3c
Summary:
It adds a model of vector::push_back
Depends on D16687225
Reviewed By: ezgicicek
Differential Revision: D16687269
fbshipit-source-id: 9d2a73fca
Summary:
It enables pruning of vector's size when the return value of the function call of `vector::size` is pruned.
Depends on D16687167
Reviewed By: ezgicicek
Differential Revision: D16687225
fbshipit-source-id: 793a21b3a
Summary:
It generates vector value ondemand when it is given as a parameter.
Depends on D16645589
Reviewed By: ezgicicek
Differential Revision: D16645624
fbshipit-source-id: 7498c8ab2
Summary:
These have proved to be too fragile to maintain as they would often break
compilation of user code. They have been off by default for more than a year
now (D7350715).
Removing the include models shows a more accurate picture of what infer results
look like in production. As such, lots of tests have changed, mostly
biabduction but also in inferbo. SIOF was using include-based models too but
now libc++ is better and iostreams are implemented in a way that SIOF
understands (instead of being magical creatures) so nothing changed there.
Reviewed By: skcho
Differential Revision: D16602171
fbshipit-source-id: ce38f045b
Summary:
This diff prevents that the latest prune value is overwritten as top
from callees.
Reviewed By: jvillard
Differential Revision: D16540391
fbshipit-source-id: bdd5b42ed
Summary:
This diff improves the precision of the mod operator.
For example, result of x % c (when x>=0 and c>0) is
(before) [0, c-1]
(after) [0, min(c-1,x)]
Reviewed By: ezgicicek
Differential Revision: D16518578
fbshipit-source-id: a68660ee7
Summary:
Pulse didn't treat local variables going out of scope as invalidating the corresponding address in memory. This diff fixes that by
- marking all local variables that exits the scope with the attribute `AddressOfStackVariable`
- before we write the summary for the proc, we make sure to invalidate all such addresses local to the procedure as `Invalid.` If such an address is read, then we would raise a use-after-lifetime issue.
Reviewed By: jvillard
Differential Revision: D16458355
fbshipit-source-id: 3686524cb
Summary:
It downgrades issues of void pointer to L5, because of its impreciseness. This is not
ideal but Inferbo cannot analyze arrays pointed by void pointers precisely at the moment.
Reviewed By: jvillard
Differential Revision: D16379911
fbshipit-source-id: f2c016aba
Summary:
A common gotcha is the new test. Model the minimum amount of
`std::basic_string` to catch it.
Reviewed By: mbouaziz, ngorogiannis
Differential Revision: D16121090
fbshipit-source-id: 66f06cb43
Summary:
Be more flexible in what type of function calls are allowed in `ViaCall ...` actions to be able to include models.
Also get rid of `here here` in traces /o\
As a side-effect, get more precise (=qualified) procedure names in
traces (but not in messages so as not to be too verbose).
Reviewed By: mbouaziz, ngorogiannis
Differential Revision: D16121092
fbshipit-source-id: fb51b02f8
Summary:
Replaced by pulse. `--ownership` is now a deprecated form of `--pulse`.
The ownership checker is starting to give wrong answers due to changes in the
clang frontend, so it's better to remove it in favour of pulse.
there_goes_my_hero
Reviewed By: ngorogiannis
Differential Revision: D16107650
fbshipit-source-id: bb2446a19
Summary:
So it turns out we need to translate even more cases. Pulse had a FP
before that this fixes.
Reviewed By: ezgicicek
Differential Revision: D16073629
fbshipit-source-id: c03460b5a
Summary:
This is needed to test some functionality in the next diff. Only one
test changes (no longer a FN), which is now documented. Also, stop
including the "header models" meant for biabduction!
Maybe one day we'll need to have several test modes for different C++
versions. Seems overkill for now, so let's wait until we see some actual
issues (eg FPs) that manifest in one version but not the other.
Reviewed By: mbouaziz
Differential Revision: D16073630
fbshipit-source-id: 1cfdfc933
Summary:
Sometimes the post of a function call has attributes on addresses that
were mentioned in the pre but are no longer reachable in the post. We
don't want to forget these, see added test.
Reviewed By: mbouaziz
Differential Revision: D16050050
fbshipit-source-id: 1ce522b97
Summary:
The previous code would call the destructor for the C++ temporary
*before* the prune nodes, which then try to dereference it. Wrong.
Quick fix: don't destroy temporaries in conditionals.
Reviewed By: mbouaziz
Differential Revision: D16030735
fbshipit-source-id: e11abad58
Summary:
We were skipping some instructions before and that was a problem for
pulse. See added pulse test.
Reviewed By: mbouaziz
Differential Revision: D16030150
fbshipit-source-id: 9c62e6213
Summary: Not sure if anyone uses this but there, now it's modelled.
Reviewed By: mbouaziz
Differential Revision: D16008162
fbshipit-source-id: f4795dcba
Summary:
Prevent false positives about variables captured by value gone out of
scope.
Reviewed By: ezgicicek
Differential Revision: D16008165
fbshipit-source-id: d70e47db4
Summary: We know how to do interprocedural calls so let's use that!
Reviewed By: mbouaziz
Differential Revision: D16008164
fbshipit-source-id: 4c34bf704
Summary:
`function::operator=` is called whenever we assign a literal lambda to a
variable, so it's pretty useful to be able to report anything on
lambdas.
Reviewed By: mbouaziz
Differential Revision: D16008163
fbshipit-source-id: a9d07668d
Summary:
Printing `Exp.Const (Cfun proc_name)` adds `_fun_` in front of the
procedure name, eg `_fun_foo` instead of `foo`. This showed up in pulse
traces.
Reviewed By: mbouaziz
Differential Revision: D16004606
fbshipit-source-id: 72ac6866f
Summary:
Fixes a false positive where the address of a C++ temporary is bound to
a static const reference variable then returned. The fix doesn't try to
establish that the variable is a const reference so could lead to false
negatives but that can be addressed later.
Reviewed By: ezgicicek
Differential Revision: D16004538
fbshipit-source-id: e403dbefe
Summary:
[apologies for the unreviewable diff...]
Get rid of HIL expressions in pulse. This finishes the HIL -> SIL
migration. The first step made pulse start from SIL instructions but
would translate most accesses to HIL to re-use most of the existing
pulse code. This diff gets rid of the intermediate translation of SIL
expressions to HIL expressions.
Big changes:
1. `PulseOperations` mostly rewritten, driven by using `Exp.t` instead of `HilExp.AccessExpression.t` for everything.
2. Stop trying to reverse-engineer what addresses mean in terms of
access paths from program variables. Rely on the trace pointing at
the right places in the code to be enough. This is because it wasn't
that useful (and could even be misleading when wrong) but could be
prohibitively expensive in degenerate cases (eg nodes with tens of
thousands of successive array accesses...)
3. `PulseAbductiveDomain.apply_post` now returns the computed return
value instead of recording it itself.
4. Change of vocabulary: `materialize` -> `eval`, `crumb` -> `event`
5. Function calls arguments are now evaluated prior to doing anything
else, which saves everything else from having to (remember to) do
that. In particular, this changes how models look quite a bit.
Reviewed By: mbouaziz
Differential Revision: D15986373
fbshipit-source-id: 1d79935de
Summary: Inject destructor calls to destroy a temporary when its lifetime ends.
Reviewed By: mbouaziz
Differential Revision: D15674209
fbshipit-source-id: 0f783a906
Summary:
Now that HIL doesn't help us anymore we need to reconstruct its mapping
"SIL logical var -> program access path". We already have everything we
need in pulse: it suffices to walk the current memory graph starting
from program variables until we find the value of the temporary we are
interested in.
This diff also builds some type machinery to make sure all accesses are
explained.
Reviewed By: mbouaziz
Differential Revision: D15824959
fbshipit-source-id: 722c81b39
Summary:
It turns out HIL gets in the way of a precise heap analysis. For
instance, instead of:
```
n$0 = *&x.f
_ = delete(&x)
*&y = n$0
```
HIL tries hard to forget about intermediate variables and shows instead
```
_ = delete(&x)
*&y = *&x.f
```
Oops, that's a use-after-delete, whereas the original code was safe.
While it's easy to write SIL programs that are completely unsound for
HIL, they are not generated very often from the frontends. In fact, the
problem became apparent only when making the clang frontend translate
C++ temporaries destructors, which produces the situation above
routinely.
This diff makes the minimal amount of change to make Pulse build and
produce equivalent results (minus HIL bugs) starting from SIL instead of
HIL. The reporting sucks for now because we need to translate SIL
temporaries back into program access paths. This is done in the next
diff.
Reviewed By: mbouaziz
Differential Revision: D15824961
fbshipit-source-id: 8e4e2a3ed
Summary:
This one isn't caught because we don't destruct temporaries that are
bound to a const reference. According to the C++ standard these should
get destroyed when the const reference gets destroyed but instead we
just don't destroy them for now.
Reviewed By: mbouaziz
Differential Revision: D15760209
fbshipit-source-id: 32c935ec0
Summary:
In a next diff temporaries will get destructed at the end of their
lifetimes and that naive model would be causing false positives.
The flipside is that we lose all reports on closures for now, will need
to model them separately later.
Reviewed By: mbouaziz
Differential Revision: D15695943
fbshipit-source-id: c2c482c02
Summary:
This started as an attempt to understand how to modify the frontend to
inject destructors for C++ temporaries (see next diffs).
This diff rewrites the existing logic for computing the list of
variables that should be destroyed at the end of each statement, either
because it's the end of their syntactic scope or because control flow
branches outside of their syntactic scope.
The frontend translates a function from the last instructions to the
first, but scope computation needs to be done in the other direction, so
it's done in a separate pass *before* the main translation happens. That
first pass creates a map from statements in the AST to the list of
variables that should be destroyed at the end of these statements. This
is still the case now.
Before, that map would be computed in a bit of a weird way: scopes are
naturally a stack but instead of that the structure maintained was a
flat list + a counter to know where the current scope ended in that
list.
In this diff, redo the computation maintaining a stack of scopes
instead, which is a bit cleaner. Also treat more instructions as
introducing a new scope, eg if, for, ...
Reviewed By: mbouaziz
Differential Revision: D15674208
fbshipit-source-id: c92429e82
Summary:
Somewhat trivial: add a string to "Destruction" nodes to indicate why
they were created. Rename the main `instruction_aux` function into
`instruction_translate` (see next diff for why).
Reviewed By: mbouaziz
Differential Revision: D15674211
fbshipit-source-id: 8a7eda72c
Summary:
I rewrote the test so it doesn't need any C++ headers so that:
- it's easier to see what's going on
- it's easier to debug: the whole AST is now somewhat readable vs before
the headers made it impossibly long
Reviewed By: ezgicicek
Differential Revision: D15674213
fbshipit-source-id: d98941983
Summary:
The synthetic methods from `topl.Property` are now nonempty: they
simulate a nondeterministic automaton.
Reviewed By: jvillard
Differential Revision: D15668471
fbshipit-source-id: 050408283
Summary:
- take advantage more structured attributes in the exported AST
- circumvent new format of `if` and `switch`
- a few new features/nodes but nothing major there
update-submodule: facebook-clang-plugins
Reviewed By: mbouaziz, martintrojer
Differential Revision: D15453572
fbshipit-source-id: c0c24345f
Summary:
This messes with the deduplication heuristic when templated function
names show up in the error messages, since the heuristic demands that
the error messages are the same.
Reviewed By: mbouaziz
Differential Revision: D15374333
fbshipit-source-id: 70232d254
Summary:
Improve the error messages, change is more or less documented in the
code.
Reviewed By: mbouaziz
Differential Revision: D15374334
fbshipit-source-id: f1dd54180
Summary:
Before: the trace would explain how a value was invalidated and
accessed, but not how the value that was invalidated had been
constructed.
Now: `PulseTrace.t` records breadcrumbs of how the value was constructed
in addition to the interproc "action" trace leading to the invalidation
or access action.
Concretely:
```
void bad(X &x) {
X *y = x;
X *z = x;
delete y;
access(z);
}
```
will produce the trace:
Invalidation part:
y = x
delete y
Access part:
z = x
access(z)
access to z->f inside of access(z)
Before this diff the "Access part" would be missing the "z = x" part of
the trace, so it might be confusing why `z` has anything to do with `y`.
However, such "breadcrumbs" are not recorded in the inter-procedural
part, only the sequence of calls is. This is a trade-off for simplicity,
maybe it's enough for developers maybe it isn't, we'll find out later.
Reviewed By: jberdine
Differential Revision: D15354438
fbshipit-source-id: 8d0aed717
Summary:
Feedback from peterogithub:
- mention which access path is being invalidated and accessed in the message
- mention the line at which it was invalidated (the line at which it's accessed is already the line at which we report)
- traces for stack variable/C++ temporary address escapes
- delete double implementation of the same functionality in
`PulseTrace`: `location_of_action_start` is the same as
`outer_location_of_action`...
Reviewed By: jberdine
Differential Revision: D14800294
fbshipit-source-id: 3d9ab9b3d
Summary:
Similarly to function parameters (and the return value), we need to
apply the pre/post of a function call to the globals mentioned in its
summary.
- tigthen summaries further to remember only abducible variables in the
post (as well as in the pre)
- take globals into account when applying pre/post pairs
Reviewed By: jberdine
Differential Revision: D14780800
fbshipit-source-id: fc0d180bb
Summary:
The heuristic to detect variables going out of scope was to detect any
access expression passed as argument to an injected destructor call.
However destructor calls are also injected in destructor bodies to
destruct each field of an object, so the heuristic would detect fields
going out of scope, which, erm, doesn't make sense. Limit the heuristic
to local program variables.
Reviewed By: jberdine
Differential Revision: D14771454
fbshipit-source-id: ffa3c9fe3
Summary:
Only throw values to the pre if they can be followed from "abducible"
variables: formals of the current method and globals.
Because figuring out if a `Pvar.t` is a formal of the current procedure
is actually a giant pain, hack something not too bad instead:
pre-register all formals at the start of the analysis of the
procedure. Then the only other variables we care about in the
precondition are globals, which we can detect easily.
This is mostly an optimisation (summaries won't include irrelevant
"abduced" facts about the procedure's local variables anymore), but it
also fixes a bug where we would sometimes overwrite things in the pre. I
think that's why the tests improved.
Reviewed By: ngorogiannis
Differential Revision: D14753493
fbshipit-source-id: 08e73637f
Summary:
This mostly doesn't make sense. The only thing this would have been good
for was to give the most accurate result on access paths such as
`*(&(x.f))`, but these are normalised anyway (into `x.f`) so we actually
never see these. That said there might be some use to some similar logic
in the future, but in the meantime let's delete the current feature as
it wasn't thought through.
Reviewed By: ezgicicek
Differential Revision: D14753492
fbshipit-source-id: 597cec027
Summary:
The previous message formatting had regressed and produced non-sensical messages.
More importantly, remove template parameters from error messages to
trigger the heuristic in `InferPrint` that deduplicates errors that are
on the same line with the same error type and message. Without this we
get hundreds of reports that correspond to as many instantiations of the
same code.
Reviewed By: ngorogiannis
Differential Revision: D14747979
fbshipit-source-id: 3c4aad2b1
Summary:
We see the magic function `__variable_initialization` at the point where
the variable is declared, eg `int x = foo()`. It's safe to reset `&x` at
that point. This circumvents an issue that pops up in some rare cases
where the ternary conditional operator `?:` and variable initialization
conspire to produce weird frontend results.
Some test becomes a FN again, but I think it was being reported for the
wrong reasons; will investigate more later.
Reviewed By: ngorogiannis
Differential Revision: D14747980
fbshipit-source-id: e75d6e30f
Summary:
This ensures that each attribute type can only be present once per
address. Makes ~80x time improvement on pathological cases such as
Duff's device.
This introduces a new kind of Set in `PrettyPrintable`.
Reviewed By: mbouaziz
Differential Revision: D14645091
fbshipit-source-id: c7f9b760c
Summary:
Detect when a variable goes out of scope. When that's the case, mark its
address *and* its contents as invalid.
Give subsequent uses a USE_AFTER_LIFETIME error type instead of
USE_AFTER_DESTRUCTOR.
Reviewed By: jberdine
Differential Revision: D14387147
fbshipit-source-id: a2c530fda
Summary:
Instead of emitting an ad-hoc builtin on variable declaration emit a new
metadata instruction. This allows us to remove the code matching on that
ad-hoc builtin that had to be inserted in several checkers.
Inferbo & pulse used that information meaningfully and had to undergo
some minor changes to cope with the new metada instruction.
Reviewed By: ezgicicek
Differential Revision: D14833100
fbshipit-source-id: 9b3009d22
Sungkeun Cho
Ezgi Çiçek
Dulma Churchill
Jules Villard
Daiva Naudziuniene
Nikos Gorogiannis
Mitya Lyubarskiy
Martin Trojer
Josh Berdine
Radu Grigore
Peter O'Hearn
Jeremy Dubreil
David Lively
Lee Howes