This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH] Fix strict-aliasing warning in resolv/res_hconf.c
- From: Florian Weimer <fweimer at redhat dot com>
- To: Pedro Alves <palves at redhat dot com>, sellcey at imgtec dot com
- Cc: Andreas Schwab <schwab at suse dot de>, Roland McGrath <roland at hack dot frob dot com>, Paul Eggert <eggert at cs dot ucla dot edu>, libc-alpha at sourceware dot org
- Date: Tue, 26 May 2015 21:23:02 +0200
- Subject: Re: [PATCH] Fix strict-aliasing warning in resolv/res_hconf.c
- Authentication-results: sourceware.org; auth=none
- References: <5bfa6373-3817-4d31-a5ee-a8676e79b723 at BAMAIL02 dot ba dot imgtec dot org> <555BB55E dot 3050304 at cs dot ucla dot edu> <1432075989 dot 16668 dot 62 dot camel at ubuntu-sellcey> <555BC19B dot 90001 at cs dot ucla dot edu> <1432077972 dot 16668 dot 65 dot camel at ubuntu-sellcey> <20150519235817 dot 9516F2C3A73 at topped-with-meat dot com> <555C3E0B dot 2040404 at redhat dot com> <mvma8wzbqsv dot fsf at hawking dot suse dot de> <555C48F0 dot 2030208 at redhat dot com> <1432139240 dot 16668 dot 77 dot camel at ubuntu-sellcey> <555F1430 dot 5050301 at redhat dot com> <5564C673 dot 4040007 at redhat dot com>
On 05/26/2015 09:16 PM, Pedro Alves wrote:
> On 05/22/2015 12:34 PM, Florian Weimer wrote:
>>
>> But from a API risk perspective, adding the member is fine—I think,
>> others might disagree. There is no ABI risk because of the existing
>> padding in struct sockaddr.
>
> Is the union's alignment before/after the same?
Good point.
As far as I can tell, the alignment inside struct ifaddrs does not
change because there is an unsigned int member which forces 4 byte
alignment. Otherwise the interface would not have worked on
strict-alignment architectures because struct sockaddr lacks an
alignment specification. Wow. This is stuff is *broken*.
--
Florian Weimer / Red Hat Product Security