Summary:
When we create Dereference edge, we also create TakeAddress back edge. This causes false positives for stack variables. When we write to a stack variable and then take its address, the resulting address is the one from the back edge of the written value. See example `push_back_value_ok`. To solve this issue, this diff changes stack to denote a map from address of variables rather than from variables.
We still have issue for fields, see example, FP_push_back_value_field_ok. To solve this, we probably need to remove back edges.
Reviewed By: jvillard
Differential Revision: D13432415
fbshipit-source-id: 9254a1a6d
Summary: Mostly a revert of D13190876 once the disjunctive domain is in place.
Reviewed By: da319
Differential Revision: D13432488
fbshipit-source-id: f1e98ef0d
Summary:
Change join/widen policies to more interesting ones and play around to
find a good tradeoff.
Reviewed By: mbouaziz
Differential Revision: D13432492
fbshipit-source-id: 2c3e498dd
Summary:
Introduce machinery to do disjunctive HIL domains and use it for pulse,
but only in a mode that preserves the existing behaviour.
The disjunctive domain is a functor that turns any (HIL for now)
transfer function module into one operating on sets of elements of the
original domain. The behaviour of joins (and widenings, which are equal
to joins) can be chosen when instantiating the functor among 3
behaviours:
- `` `JoinAfter n`: when the set of disjuncts gets bigger than `n` the
underlying domain's join is called to collapse them into one state
- `` `UnderApproximateAfter n`: when the sest of disjuncts gets bigger
than `n` then just stop adding new states to it, drop any further states
on the floor. This corresponds to an under-approximation/bounded
approach.
- `` `NeverJoin`
The widening is always of the form ``
`UnderApproximateAfterNumIterations max_iter` for now since the only
user is pulse and I'm not sure what else would be useful.
Picking `` `JoinAfter 0` gives the same results as the non-disjunctive
domain since the underlying `join` will always be called. Make pulse use
this mode for now, and tune it in a next diff.
Reviewed By: mbouaziz
Differential Revision: D13431375
fbshipit-source-id: b93aa50e7
Summary:
This will be useful to make the analysis more precise. In particular, it
allows a disjunctive version of pulse to deal will deleting vector
elements in a loop: without this, deleting an array element in one
iteration will make the analysis think that the next array element is
invalid too since they are all the same. By keep track of the index, we
can detect when we are sure that two elements are the same and only
report in that case.
Reviewed By: ngorogiannis
Differential Revision: D13431374
fbshipit-source-id: dae82deeb
Summary:
A lot of functors that take a `Make{SIL,HIL}` can take a `{SIL,HIL}`
directly instead. This makes my head hurt a bit less.
Reviewed By: mbouaziz
Differential Revision: D13416967
fbshipit-source-id: eb0b33bc4
Summary:
When a lambda gets created, record the abstract addresses it captures, then
complain if we see some of them be invalidated before it is called.
Add a notion of "allocator" for reporting better messages. The messages are
still a bit sucky, will need to improve them more generally at some point.
```
jul lambda ~ infer 1 infer -g --pulse-only -- clang -std=c++11 -c infer/tests/codetoanalyze/cpp/pulse/closures.cpp
Logs in /home/jul/infer.fb/infer-out/logs
Capturing in make/cc mode...
Found 1 source file to analyze in /home/jul/infer.fb/infer-out
Found 2 issues
infer/tests/codetoanalyze/cpp/pulse/closures.cpp:21: error: USE_AFTER_DESTRUCTOR
`&(f)` accesses address `s` captured by `&(f)` as `s` invalidated by destructor call `S_~S(s)` at line 20, column 3 past its lifetime (debug: 5).
19. f = [&s] { return s.f; };
20. } // destructor for s called here
21. > return f(); // s used here
22. }
23.
infer/tests/codetoanalyze/cpp/pulse/closures.cpp:30: error: USE_AFTER_DESTRUCTOR
`&(f)` accesses address `s` captured by `&(f)` as `s` invalidated by destructor call `S_~S(s)` at line 29, column 3 past its lifetime (debug: 8).
28. f = [&] { return s.f; };
29. }
30. > return f();
31. }
32.
Summary of the reports
USE_AFTER_DESTRUCTOR: 2
```
Reviewed By: da319
Differential Revision: D13400074
fbshipit-source-id: 3c68ff4ea
Summary: Model more `std::vector` functions that can potentially invalidate references to vector's elements (https://en.cppreference.com/w/cpp/container/vector).
Reviewed By: mbouaziz
Differential Revision: D13399161
fbshipit-source-id: 95cf2cae6
Summary:
Some code calls `this->~Obj()` then proceeds to use fields in the current
object, which previously we would report as invalid uses. Assume people know
what they are doing and ignore destructor calls to `this`.
Reviewed By: mbouaziz
Differential Revision: D13401145
fbshipit-source-id: f6b0fb6ec
Summary:
`AccessExpression.t` represents array accesses as `ArrayOffset of t * Typ.t * t
list`, i.e. the index is represented by a list of access expressions. This is
not precise enough when indices cannot be represented as such. In fact, in
general any `HilExp.t` can be an array index but this type was an approximation
that was good enough for existing checkers based on HIL.
This diff changes the type of access expressions to be parametric in the type
of array offsets, and uses this to record `HilExp.t` into them when translating
from SIL to HIL.
To accomodate the option of not caring about array offsets
(`include_array_indexes=false`), the type of array offsets is an option type.
Reviewed By: mbouaziz
Differential Revision: D13360944
fbshipit-source-id: b01442459
Summary:
`AccessExpression.t` and `HilExp.t` are about to become mutually
recursive, this will help distinguish the actual changes from the moving
of code around.
This deletes the file left around in the previous commit to preserve
callers of `AccessExpression`.
Reviewed By: mbouaziz
Differential Revision: D13377645
fbshipit-source-id: 71338d1f3
Summary:
`AccessExpression.t` and `HilExp.t` are about to become mutually
recursive, this will help distinguish the actual changes from the moving
of code around.
Reviewed By: mbouaziz
Differential Revision: D13377644
fbshipit-source-id: 9d6f290b6
Summary:
This will be useful for proper support of array indexes in pulse and in
HIL in general.
Reviewed By: mbouaziz
Differential Revision: D13377642
fbshipit-source-id: e431121fb
Summary: It weakly updates array when there are more than two contents.
Reviewed By: mbouaziz
Differential Revision: D13318443
fbshipit-source-id: fa740d8b1
Summary:
It materializes symbolic values of function parameters on-demand. The on-demand materialization is triggered when finding a value from an abstract memory and joining/widening abstract memories.
Depends on D13294630
Main idea:
* Symbolic values are on-demand-ly generated by a symbol path and its type
* In order to avoid infinite generation of symbolic values, symbol paths are canonicalized by structure types and field names (which means they are abstracted to the same value). For example, in a linked list, a symbolic value `x->next->next` is canonicalized to `x->next` when the structures (`*x` and `*x->next`) have the same structure type and the same field name (`next`).
Changes from the previous code:
* `Symbol.t` does not include `id` and `pname` for distinguishing symbols. Now, all symbols are compared by `path:SymbolPath.partial` and `bound_end`.
* `SymbolTable` is no longer used, which was used for generating symbolic values with new `id`s.
Reviewed By: mbouaziz
Differential Revision: D13294635
fbshipit-source-id: fa422f084
Summary:
`eval_locs` is like `eval |> get_all_locs` but avoids computing things that aren't necessary.
The goal was not to be an optimization but is needed for Java where array blocks don't have offsets.
Reviewed By: skcho
Differential Revision: D13190939
fbshipit-source-id: 1cc0e6338
Summary: Similarly as `std::vector::push_back`, `std::vector::reserve` can invalidate the references to elements if the new size is bigger than the existing one. More info on `std::vector::reserve`: https://en.cppreference.com/w/cpp/container/vector/reserve
Reviewed By: jvillard
Differential Revision: D13340324
fbshipit-source-id: bf99b6923
Summary: Moving all the files related to nullable type checking under the same directory. The goal is to merge everything into the same backend based on the AI framework and access expressions.
Reviewed By: ngorogiannis
Differential Revision: D13350880
fbshipit-source-id: 8ab3cf81b
Summary: Instead of variable having the value of a single location on stack, we now allow variables to have multiple locations. Consequently, we also allow a memory location to point to a set of locations in the heap. We enforce a limit on a maximum number of locations in a set (currently 5).
Reviewed By: jvillard
Differential Revision: D13190876
fbshipit-source-id: 5cb5ba9a6
Summary:
At function calls, it copies callee's values that are reachable from parameters.
Depends on D13231291
Reviewed By: mbouaziz
Differential Revision: D13231711
fbshipit-source-id: 1e8aed1c4
Summary: It instantiates not only symbols for bound but also symbols for locations at function calls.
Reviewed By: mbouaziz
Differential Revision: D13231291
fbshipit-source-id: ce23a943b
Summary: Recent improvements in join fixed `FP_allocate_in_branch_ok` because the variable was not read after the join.
Reviewed By: mbouaziz
Differential Revision: D13233441
fbshipit-source-id: 89b701e12
Summary:
It adds symbolic locations for paramters, which will be used for fixing instantiations of parameters in the
following diffs.
Reviewed By: mbouaziz, jvillard
Differential Revision: D13214293
fbshipit-source-id: f016ea4c3
Summary: Delete function that would get a linter warning or not depending on the version of Xcode.
Reviewed By: martintrojer
Differential Revision: D13215750
fbshipit-source-id: 886ce397d
Summary: It is not used yet and still manages to cause false positives.
Reviewed By: mbouaziz
Differential Revision: D13102948
fbshipit-source-id: 2122666c2
Summary:
It's useful for checkers to know when variables go out of scope to
perform garbage collection in their domains, especially for complex
domains with non-trivial joins. This makes the analyses more precise at
little cost.
This could have been added as a custom function call to a builtin, but I
decided against it because this instruction doesn't have the semantics
of any function call. It's better for each checker to explicitly not
deal with the custom instruction instead.
Reviewed By: jberdine
Differential Revision: D13102951
fbshipit-source-id: 33be22fab
Summary:
Before, the liveness pre-analysis would place extra instructions in the
CFG for either:
1. marking an `Ident.t` as dead, or
2. marking a `Pvar.t` as `= 0`
But we have no way of marking pvars dead without setting them to 0. This
is bad because setting pvars to 0 is not possible everywhere they are
dead. Indeed, we only do it when we haven't seen their address being
taken anyway. This prevents the following situation, recorded in our tests:
```
int address_taken() {
int** x;
int* y;
int i = 7;
y = &i;
x = &y;
// if we don't reason about taken addresses while adding nullify instructions,
// we'll add
// `nullify(y)` here and report a false NPE on the next line
return **x;
}
```
So we want to mark pvars as dead without nullifying them. This diff
extends the `Remove_temps` SIL instruction to accept pvars as well, and
so renames it to `ExitScope`.
Reviewed By: da319
Differential Revision: D13102953
fbshipit-source-id: aa7f03a52
Summary:
Switches from opam 1 to opam 2.
Opam2 has some cool new features that simplify some of the scripting.
Notable changes:
1. Use the new `opam lock` *plugin* from https://github.com/AltGr/opam-lock/ instead of https://github.com/rgrinberg/opam-lock. This has a simpler interface for our purposes.
2. Change the way `./build-infer.sh` can be called to use an already existing switch: simply pass `--user-opam-switch` to the script and it won't attempt to create/set the current switch. This can be used to build infer in a local switch for instance.
3. Take advantage of automatic pinning where possible, eg to install infer deps without using opam.locked.
Reviewed By: ngorogiannis
Differential Revision: D13167863
fbshipit-source-id: 1a667c270
Summary:
It removes the `represents_multiple_values` parameters when we can know them from `path` values.
Depends on D12939124
Reviewed By: skcho
Differential Revision: D12939130
fbshipit-source-id: 30ff768b2
Summary:
It modifies sizes and offsets of array values on pointer castings.
Currently, it supports only simple castings of pointer-to-integers.
Reviewed By: mbouaziz
Differential Revision: D12920589
fbshipit-source-id: a5ba831b8
Summary: In this diff, it passes the parameter of integer type widths to evaluation functions. The parameter which will be used for casting in the following diff.
Reviewed By: mbouaziz
Differential Revision: D12920581
fbshipit-source-id: 48bbc802b
Summary:
It enables the translation of casting expression. As of now, it
translates only the castings of pointers to integer types, in order to
avoid too much of change, which may mess the checkers up.
Reviewed By: jvillard
Differential Revision: D12920568
fbshipit-source-id: a5489df24
Summary:
Useful to understand the changes in the pre-analysis, or to inspect the
CFG that checkers actually get.
This means that the pre-analysis always runs when we output the dotty,
but I don't really see a reason why not. In fact, we could probably
*always* store the CFGs as pre-analysed.
Reviewed By: mbouaziz
Differential Revision: D13102952
fbshipit-source-id: 89f3102ec
Summary: It fixes the conditions of the `check` function to address `is_collection_add` cases correctly.
Reviewed By: mbouaziz
Differential Revision: D13081281
fbshipit-source-id: 39ae5ef03
Summary: Experimental feature: Use memcached for summaries as a look-aside cache during analysis.
Reviewed By: jvillard
Differential Revision: D12939311
fbshipit-source-id: 9f78994e2
Summary:
Currently, if there are several reports on the same line, the most important one is reported together with a message containing how many reports were suppressed.
This is sometimes causing the bug hash we use believe that a report is introduced (eg if the number of suppressed reports changes).
Reviewed By: mbouaziz
Differential Revision: D13067306
fbshipit-source-id: 1cc0c6d3a
Summary:
Messages emitted by cost-analysis now look like the following:
Complexity of this function has **increased** from `O(1)` to `O(n)`.
Reviewed By: mbouaziz
Differential Revision: D13058008
fbshipit-source-id: 119037703
Summary:
Update clang plugin which now gives names to variables captured by lambdas that were empty before.
update-submodule: facebook-clang-plugins
Reviewed By: jvillard
Differential Revision: D12979015
fbshipit-source-id: 0b092fb24
Summary:
It turns out keeping attributes (such as invalidation facts) separate
from the memory is a bad idea and leads to loss of precision and false
positives, as seen in the new test (which previously generated a
report).
Allow me to illustrate on this example, which is a stylised version of
the issue in the added test: previously we'd have:
```
state1 = { x = 1; invalids={} }
state2 = { x = 2; invalids ={1} }
join(state1, state2) = { x = {1, 2}; invalids={{1, 2}} }
```
So even though none of the states said that `x` pointed to an invalid
location, the join state says it does because `1` and `2` have been
glommed together. The fact `x=1` from `state1` and the fact "1 is
invalid" from `state2` conspire together and `x` is now invalid even
though it shouldn't.
Instead, if we record attributes as part of the memory we get that `x`
is still valid after the join:
```
state1 = { x = (1, {}) }
state2 = { x = (2, {}) }
join(state1, state2) = { x = ({1, 2}, {}) }
```
Reviewed By: mbouaziz
Differential Revision: D12958130
fbshipit-source-id: 53dc81cc7
Summary:
I hear that this scheduler is better. I want the best scheduler
possible. Also pulse's join is a bit complex so it might matter one day.
whydididothis
Reviewed By: mbouaziz
Differential Revision: D12958131
fbshipit-source-id: 3bd77ccba
Summary: There is a bug on the instantiation of function parameters.
Reviewed By: mbouaziz
Differential Revision: D12973691
fbshipit-source-id: ca7fbc4e6
Summary: The aligned width of bool should be 1-byte, while the range of bool [0,1].
Reviewed By: jvillard
Differential Revision: D12932394
fbshipit-source-id: be1a5d6d1
Summary: For a general case of `operator=` we want to create a fresh location for the first parameter as `operator=` behaves as copy assignment.
Reviewed By: jvillard
Differential Revision: D12940635
fbshipit-source-id: 89c6e530d
Summary:
Whenever `vec.reserve(n)` is called, remember that the vector is
"reserved". When doing `vec.push_back(x)` on a reserved vector, assume
enough size has been reserved in advance and do not invalidate the
underlying array.
This gets rid of false positives.
Reviewed By: mbouaziz
Differential Revision: D12939837
fbshipit-source-id: ce6354fc5
Summary:
Instead of keeping at most one invalidation fact for each address, keep
a set of them and call them "attributes". Keeping a set of invalidation
facts is redundant since we always only want the smallest one, but
makes the implementation simpler, especially once we add more kinds of
attributes (used for modelling, see next diffs).
Reviewed By: mbouaziz
Differential Revision: D12939839
fbshipit-source-id: 4a54c2132
Summary:
Copied on the ownership checker logic: return the initial value of the
domain as return. This can probably be improved.
Reviewed By: mbouaziz
Differential Revision: D12888102
fbshipit-source-id: 9e2dac7fc
Summary:
When initialising a variable via semi-exotic means, the frontend loses
the information that the variable was initialised. For instance, it
translates:
```
struct Foo { int i; };
...
Foo s = {42};
```
as:
```
s.i := 42
```
This can be confusing for backends that need to know that `s` actually
got initialised, eg pulse.
The solution implemented here is to insert of dummy call to
`__variable_initiazition`:
```
__variable_initialization(&s);
s.i := 42;
```
Then checkers can recognise that this builtin function does what its
name says.
Reviewed By: mbouaziz
Differential Revision: D12887122
fbshipit-source-id: 6e7214438
Summary:
Now that arrays are dealt with separately (see previous diff), we can
turn the join back into an over-approximation as far as invalid
locations are concerned.
Reviewed By: skcho
Differential Revision: D12881989
fbshipit-source-id: fd85e49c0
Summary:
Arrays are the main source of false positives that prevent us from
having a better (less under-approximate) join in general. The next diff
improves join and I split this off to make it easier to review.
Reviewed By: mbouaziz
Differential Revision: D12881986
fbshipit-source-id: 5f52dea27
Summary:
This prevents the join from wrongly assuming that we haven't seen a
variable on one side of the join.
Reviewed By: skcho
Differential Revision: D12881987
fbshipit-source-id: 42a776adb
Summary:
Smaller numbers are easier to read and abstract addresses should never
be shared across functions anyway.
Reviewed By: da319
Differential Revision: D12881988
fbshipit-source-id: f9bcfa343
Summary:
As explained in the added comment, clang started adding `-faddrsig` at the end
of every `-cc1` command, which trumps our heuristic for finding the file name
(thus we would write debug scripts to `-faddrsig.ast.sh`, do filename-based
filtering on `-faddrsig` instead of the source path, and more...). We rely on
the file name being the last argument in `-cc1` commands because so far that's
always been the case, and we don't want to parse the clang command line and
have to know about all the clang options...
Thanks martinoluca for the trick of simply passing `-fno-addrsig`!
Reviewed By: martinoluca
Differential Revision: D12921987
fbshipit-source-id: 28bebe647
Summary:
The upcoming ocamlformat has the ability to parse and format
docstrings. This requires that the docstrings conform to the ocamldoc
spec a bit more strongly. If a docstring does not parse, it is left
alone, but if it is morally ill-formed but parses by chance, it can be
reformatted incorrectly. This patch fixes the existing instances of
this problem.
Reviewed By: mbouaziz
Differential Revision: D12911937
fbshipit-source-id: 1c2eb590b
Summary:
For more deduplications of issues, this diff loosens the condition of
similar bounds. The previous condition of similar bounds was too
strict, so [0,0] and [0,+oo] were not similar.
Depends on D10851762
Reviewed By: mbouaziz
Differential Revision: D10866127
fbshipit-source-id: 4ba912a88
Mehdi Bouaziz
Fabio Milano
Daiva Naudziuniene
Jules Villard
Nikos Gorogiannis
David Lively
Ezgi Çiçek
Sungkeun Cho
Jeremy Dubreil
Ted Reed
Dino Distefano
Martino Luca
Martin Trojer
Josh Berdine