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

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

Hi,

Resending once again:

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.

Regards,
Siddhesh


ChangeLog:

2012-02-09  Siddhesh Poyarekar  <siddhesh@redhat.com>

	* nis/nss_compat/compat-initgroups.c (getgrent_next_nss,
	_nss_compat_initgroups_dyn): Fall back to malloc/free for
	large group memberships.


Date: Wed, 14 Mar 2012 18:35:43 +0530
From: Siddhesh Poyarekar <siddhesh@redhat.com>
To: libc-alpha@sourceware.org
Cc: Carlos O'Donell <carlos@systemhalted.org>, Jeff Law <law@redhat.com>
Subject: [RESEND][PATCH][BZ 13761] Fix allocation in nss_compat for
large number of memberships to a group


ping.

--
Siddhesh

--- Begin Message ---

• From: Siddhesh Poyarekar <siddhesh at redhat dot com>
• To: Carlos O'Donell <carlos at systemhalted dot org>
• Cc: libc-alpha at sourceware dot org, Jeff Law <law at redhat dot com>
• Date: Mon, 27 Feb 2012 11:46:52 +0530
• Subject: [PATCH][BZ 13761] Fix allocation in nss_compat for large number ofmemberships to a group
• References: <20120220094306.GA4753@spoyarek.pnq.redhat.com><20120222135130.GC21637@spoyarek.pnq.redhat.com><CADZpyiyKZkPBJQ4SgNrei-+dgjWasQYvgoUakjhzG6Tjcp+5Xw@mail.gmail.com>

On Fri, Feb 24, 2012 at 07:40:25PM -0500, Carlos O'Donell wrote:
> Thanks for the patch, before review could you please do the following:
> 
> (1) Work through the contribution checklist.
> 
> http://sourceware.org/glibc/wiki/Contribution checklist
> 
> For example you fail to update the copyright year.

Done, thanks for pointing out.

> (1) File a bugzilla issue for this patch.
> 
> We want to get user visible bugs into bugzilla.

Done. Updated patch and changelog follows:

http://sourceware.org/bugzilla/show_bug.cgi?id=13761

Regards,
Siddhesh

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.

Attachment: glibc-nss-compat.patch
Description: Text document

--- End Message ---