[PATCH] D11832: [Patch] [Analyzer] false positive: Potential leak connected with memcpy (PR 22954)

[pierre gousseau via cfe-commits]

pgousseau created this revision.
pgousseau added reviewers: cfe-commits, ayartsev, xazax.hun.

Dear All,

I would like to propose a patch to avoid the false positive memory leak warning kindly reported by krzysztof in https://llvm.org/bugs/show_bug.cgi?id=22954

The issue seems originates from the CString checker's handling of 'memcpy' (and string copy functions in general).
Given the below code snippet:
----------------------
struct aa { char *s; char data[32];};
...
a.s = malloc(nbytes);
memcpy(a.data, source, len);
...
----------------------
As the CString checker handles the memcpy call, it requests the invalidation of the 'a.data' region. But the invalidation worker marks the whole memory region of 'a' as to be invalidated. The Malloc checker is not made aware of this causing the false positive.

Following advices from Anton Yartsev and Gabor Horvath on cfe-dev (http://lists.cs.uiuc.edu/pipermail/cfe-dev/2015-July/043786.html), this patch introduces a new trait 'TK_DoNotInvalidateSuperRegion', for the invalidation worker to take into account, when invalidating a destination buffer of type 'FieldRegion'.

Please let me know if this is an acceptable change and if yes eventually commit it for me (as I do not have svn access) ?

Regards,

Pierre Gousseau
SN Systems - Sony Computer Entertainment

http://reviews.llvm.org/D11832

Files:
  include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
  lib/StaticAnalyzer/Checkers/CStringChecker.cpp
  lib/StaticAnalyzer/Core/RegionStore.cpp
  test/Analysis/pr22954.c

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