[cfe-dev] [Analyzer] Tips on how to fix PR22954 ? (false positive memory leak warning)

[Pierre Gousseau]

Ping !
Adding analyzer experts to cc.

Regards,

Pierre Gousseau
SN Systems - Sony Computer Entertainment

On 2 July 2015 at 09:06, Pierre Gousseau <pierregousseau14 at gmail.com> wrote:

> Dear All,
>
> I have been looking into PR22954 which has been kindly raised by krzystof
> at https://llvm.org/bugs/show_bug.cgi?id=22954 and being new to this area
> of Clang I would appreciate any tips on how to fix it.
>
> To me the root of the issue seems to originate from the CString checker as
> it performs invalidation of the destination buffer.
> Given the snippet below:
> -----------------
> 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 seems to
> consider that the whole memory region of 'a' has to be invalidated. The
> Malloc checker is not made aware of this causing the false positive.
>
> It seems a short term fix could be to detect this specific case and have
> the CString checker notify the Malloc checker that it should stop tracking
> 'a.s'.
> However this solution would reduce the number of genuine defects detected.
>
> So I would be grateful if someone could give some hints on how to provide
> the right solution.
>
> Regards,
>
> Pierre Gousseau
> SN Systems - Sony Computer Entertainment
>
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