Summary:
See added test: pulse sometimes insisted that an issue was latent even
though the condition that made it latent could not be influenced (hence
could the issue could never become manifest) by callers because it was
unrelated to the pre, i.e. it came from a mutation inside the function.
In these cases, we want to report the issue straight away instead of
keeping it latent.
Reviewed By: skcho
Differential Revision: D28002725
fbshipit-source-id: ce9e6f190
Summary:
Before returning a summary, restore formals to their initial values.
This gets rid of a false latent because the value in the path condition
is now garbage-collected.
Added a test for the tricky case of structs passed as values.
Reviewed By: skcho
Differential Revision: D28001229
fbshipit-source-id: 23dda5b43
Summary:
Whenever an equality "t = v" (t an arbitrary term, v a variable) is
added (or "v = t"), remember the "t -> v" mapping after canonicalising t
and v. Use this to detect when two variables are equal to the same term:
`t = v` and `t = v'` now yields `v = v'` to be added to the equality
relation of variables. This increases the precision of the arithmetic
engine.
Interestingly, the impact on most code I've tried is:
1. mostly same perfs as before, if a bit slower (could be within noise)
2. slightly more (latent) bugs reported in absolute numbers
I would have expected it to be more expensive and yield fewer bugs (as
fewer false positives), but there could be second-order effects at play
here where we get more coverage. We definitely get more latent issues
due to dereferencing pointers after testing nullness, as can be seen in
the unit tests as well, which may alone explain (2).
There's some complexity when adding term equalities where the term
is linear, as we also need to add it to `linear_eqs` but `term_eqs` and
`linear_eqs` are interested in slightly different normal forms.
Reviewed By: skcho
Differential Revision: D27331336
fbshipit-source-id: 7314e127a
Summary:
Adapting error messages in Pulse so that they become more intuitive for
developers.
Reviewed By: jvillard
Differential Revision: D26887140
fbshipit-source-id: 896970ba2
Summary: This diff finds a declared variable name or declared field names from trace, then constructs an error message including access paths.
Reviewed By: jvillard
Differential Revision: D26544275
fbshipit-source-id: 135c90a1b
Summary:
`add_edge_on_src` is to prepare a stack location for a local variable. Before this diff, it was
called several times for each fields.
Reviewed By: jvillard
Differential Revision: D26543715
fbshipit-source-id: 49ebf2b65
Summary:
Having different behaviours inter-procedurally and intra-procedurally
sounds like a bad design in retrospect. The model of free() should not
depend on whether we currently know the value is not null as that means
some specs are missing from the summary.
Reviewed By: skcho
Differential Revision: D26019712
fbshipit-source-id: 1ac4316a5
Summary: This diff revises the trace generation of the uninitialized value checker, by introducing a new diagnostics for it.
Reviewed By: jvillard
Differential Revision: D25433775
fbshipit-source-id: 1279c0de4
Summary:
This diff supports inter-procedural uninit analysis in pulse.
* Added `MustBeInitialized` attribute to pre state when an address is read
* Remove `Uninitialized` attribute when callee has `WrittenTo` for the
same address
Reviewed By: jvillard
Differential Revision: D25368492
fbshipit-source-id: cbc74d4dc
Summary:
This diff adds uninitialized value check in pulse. For now, it supports only simple cases,
- declared variables with a type of integer, float, void, and pointer
- malloced pointer variables that points to integer, float, void, and pointer
TODOs: I will add more cases in the following diffs.
- declared/malloced array
- declared/malloced struct
- inter-procedural checking
Reviewed By: jvillard
Differential Revision: D25269073
fbshipit-source-id: 317df9a85
Summary: The new memory leaks analysis is now ready to be enabled by default and turned on in production. This also replaces the biabduction one which is now disabled.
Reviewed By: jvillard
Differential Revision: D21998666
fbshipit-source-id: 9cd95e894
Summary:
List of things happening in this unreviewable diff:
- moved PulsePathCondition to PulseSledge
- renamed --pulse-path-conditions to --pudge
- PulsePathCondition now contains all the arithmetic of pulse
(inferbo+concrete intervals+pudge). In particular, moved arithmetic
attributes into PulsePathCondition.t. PulsePathCondition plays the
role of PulseArithmetic (combining all domains).
- added tests for a false positive involving free()
- PulseArithmetic is now just a thin wrapper around PulsePathCondition
to operate on states directly (instead of on path conditions).
- The rest is mostly moving code into PulsePathCondition (eg, from
PulseInterproc) and adjusting it.
Reviewed By: jberdine
Differential Revision: D21332073
fbshipit-source-id: 184c8e0a9
Summary:
Add a new data structure and use it for the map of memory accesses to
limit the number of destinations reachable from a given address. This
avoids remembering details of each index in large arrays, or even each
field in large structs.
Reviewed By: skcho
Differential Revision: D18246091
fbshipit-source-id: 5d3974d9c
Summary:
When encountering a constant, pulse creates an abstract value (a
variable) to represent it, and remembers that it's equal to it. The
problem is that pulse doesn't yet know how to deal with the fact that
some variables are going to be equal to each other.
This hacks around this issue in the case of constants, within the same
procedure, by remembering which constants have been assigned to which
place-holder variables, and serving those variables again when the same
constant is translated again.
Limitation: this doesn't work across procedure calls as the "constant
maps" are not saved in summaries.
Something to look out for: we don't want to make `if (p == NULL)` create
a path where `p` is invalid (we only make null invalid when we see an
assignment from 0, i.e. `p = NULL;`).
Reviewed By: ezgicicek
Differential Revision: D21089961
fbshipit-source-id: 5ebb85d0a
Summary: When looking at some reports I realised that adding the place where the memory becomes unreachable to the trace makes it more readable.
Reviewed By: skcho
Differential Revision: D20790277
fbshipit-source-id: d5df69e68
Summary:
First version of a new memory leak check based on Pulse. The idea is to examine unreachable cells in the heap and check that the "Allocated" attribute is available but the "Invalid CFree" isn't. This is done when we remove variables from the state.
Currently it only works for malloc, we can extend it to other allocation functions later.
Reviewed By: jvillard
Differential Revision: D20444097
fbshipit-source-id: 33b6b25a2
Summary:
Adding a model for malloc: we add an attribute "Allocated". This can be used for implementing memory leaks: whenever the variables get out of scope, we can check that if the variable has an attribute Allocated, it also has an attribute Invalid CFree.
Possibly we will need more details in the Allocated attribute, to know if it's malloc, or other allocation function, but we can add that later when we know how it should look like.
Reviewed By: jvillard
Differential Revision: D20364541
fbshipit-source-id: 5e667a8c3
Jules Villard
Loc Le
Gabriela Cunha Sampaio
Sungkeun Cho
Dulma Churchill