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:
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: 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: 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: 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'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:
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:
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:
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
Daiva Naudziuniene
Nikos Gorogiannis
Jules Villard
David Lively
Sungkeun Cho
Jeremy Dubreil
Ted Reed
Mehdi Bouaziz
Martino Luca