Re: [PATCH] Fix misaligned access accessing HEADER struct in res_query.c

[John David Anglin <dave dot anglin at bell dot net>]

On 2016-06-15 8:16 AM, Andreas Schwab wrote:
> Florian Weimer<fweimer@redhat.com>  writes:
>
> > >On 06/15/2016 01:42 PM, John David Anglin wrote:
> > > >>The attached patch fixes BZ 20243.  The HEADER struct needs to be packed so that
> > > >>byte accesses are used.  Tested using glibc 2.22-11on hppa.  Please install if okay.
> > >
> > > >>-} HEADER;
> > > >>+} __attribute__ ((packed)) HEADER;
> > >
> > >Unfortunately, we cannot apply this simple fix because this is a public
> > >header, and the above changes alignment of the struct.  It would also have
> > >to be __attribute__ ((__packed__)).
> It also needs to work with other compilers.

The packed attribute is used in several places in glibc.  Maybe a packed 
derivative of HEADER
can be used in res_query.c to avoid the above issue?

I don't think the packed derivative affects the layout of HEADER given 
the way the fields are
arranged.

Dave

--
John David Anglin  dave.anglin@bell.net