Subject: bug#25024: Bug in Sort

From: Paul Eggert <[email-masked]>
Date: Fri, 25 Nov 2016 10:50:06 -0800

Pádraig Brady wrote:
> for UBSAN we should probably build with
> _STRING_ARCH_unaligned defined globally
> to avoid warning for the cases we already handle.

Yes. Translating this for non-experts: the problem here is a bug in the 
bug-finding procedure, not a bug in GNU coreutils or in Gnulib.

Recent glibc (since 2016-02-18) does not define _STRING_ARCH_unaligned, which 
means that this code in gnulib md5.c etc. is no longer exercised on recent 
platforms. So in some sense the originally-reported bug is already fixed (via an 
unexpected glibc change), though this does mean Gnulib md5 etc. is now slower on 
x86-64 etc., which is a performance bug on newer platforms. If we fix the 
performance bug I suppose we'll start getting false alarms from UBSAN again.