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Re: [RESEND-2][PATCH][BZ 13761] Fix allocation in nss_compat for large number of memberships to a group


On Wednesday, March 28, 2012 12:20:37 Siddhesh Poyarekar wrote:
> On Wed, Mar 28, 2012 at 3:41 PM, Siddhesh Poyarekar
> 
> <siddhesh.poyarekar@gmail.com> wrote:
> > On Wed, Mar 28, 2012 at 3:29 PM, Andreas Jaeger <aj@suse.com> wrote:
> >>> nss_compat allocates buffer space on stack using alloca (and
> >>> extend_alloca) for initgroup and keeps extending it to fit in larger
> >>> lines. This breaks for cases where the number of members in a gorup
> >>> are very large, causing the alloca reference to go beyond thread
> >>> stack boundary. Attached patch falls back to malloc/free if the
> >>> buffer size needed is beyond __libc_alloca_cutoff.
> >> 
> >> Please state in your submission how and where this was tested.
> >> 
> >> The patch itself looks fine to me but I'd like to hear about testing,
> > 
> > I tested this using the reproducer steps described in the bug report
> > as well as with an ldap group with large number of users. I've tried
> > this on x86_64 boxes with backports of the patch to RHEL-5 (patch
> > needed modifications), RHEL-6 and also on my F-16 box with glibc built
> > off HEAD.
> 
> Updated ChangeLog with the bz number:
> 
> ChangeLog:
> 
> 2012-02-09  Siddhesh Poyarekar  <siddhesh@redhat.com>
> 
> 	[BZ #13761]
> 	* nis/nss_compat/compat-initgroups.c (getgrent_next_nss,
> 	_nss_compat_initgroups_dyn): Fall back to malloc/free for
> 	large group memberships.
> 

This is fine now, thanks,
Andreas
-- 
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