[PATCH v2] Fix use after free warning introduced by gcc 12.1

Jouni Malinen j at w1.fi
Fri Apr 28 08:39:53 PDT 2023

On Fri, Apr 21, 2023 at 12:58:21AM +0530, Krishna wrote:
> gcc 12.1 complains about using pointer after realloc as it could
> potentially be moved/freed, causing any uses after UB.
> Fix this by doing checks before alloc and use those statuses and update
> with new BSS.

Could you please provide the exact warning message produced by the
compiler? gcc 12.1 did not complain about anything in my test setup when
compiling wpa_supplicant, so I'm assuming this would need some extra
warnings to be enabled.

As far as the "use of a pointer after realloc" is concerned, it should
be noted that the implementation here does not dereference the old
pointer after the realloc() call. What is being done here is a
check of whether the buffer was indeed moved by comparing the pointer
values before and after the realloc call. Is that really UB or is that
an excessive warning from the compiler?

Jouni Malinen                                            PGP id EFC895FA

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