GNU bug report logs - #25024
build: adjust for ASAN/UBSAN

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From: Pádraig Brady <P <at> draigBrady.com>
To: Marcel Böhme <boehme.marcel <at> gmail.com>, 25024 <at> debbugs.gnu.org
Subject: bug#25024: Bug in Sort
Date: Fri, 25 Nov 2016 13:06:47 +0000

On 25/11/16 06:18, Marcel Böhme wrote:
> Dear all,
> 
> The following execution is flagged by UBSAN as undefined behaviour:
> 
> $ echo 0 > a; printf "%0.s0" {1..58} >> a
> $ ./sort -R a
> 
> UBSAN says:
> ../lib/md5.c:371:7: runtime error: load of misaligned address 0x7ffdfd45a10d for type 'const uint32_t', which requires 4 byte alignment 
> 
> So, the root cause might actually be in GNULIB. The bug was found with AFLFast, a fork of AFL.

There is some support at least for catering
for architectures where unaligned access is significant.
So for UBSAN we should probably build with
_STRING_ARCH_unaligned defined globally
to avoid warning for the cases we already handle.

cheers,
Pádraig

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