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

[Jeff Law]

On 03/29/2012 01:19 AM, Andreas Jaeger wrote:
> 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,
Installed on Siddhesh's behalf.  NEWS file updated appropriately.

Thanks,
jeff

ps.  Would it make sense for Siddhesh to have write access to the repo 
so that he can check in approved changes?