From: Johannes Weiner <hannes@cmpxchg.org>
Date: Tue, 6 Jan 2009 22:40:31 +0000 (-0800)
Subject: mm: check for no mmaps in exit_mmap()
X-Git-Tag: v2.6.27.22~14
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=664b8ee764c295ff3bfd9736094a036dcc0ebda2;p=pandora-kernel.git

mm: check for no mmaps in exit_mmap()

commit dcd4a049b9751828c516c59709f3fdf50436df85 upstream.

When dup_mmap() ooms we can end up with mm->mmap == NULL.  The error
path does mmput() and unmap_vmas() gets a NULL vma which it
dereferences.

In exit_mmap() there is nothing to do at all for this case, we can
cancel the callpath right there.

[akpm@linux-foundation.org: add sorely-needed comment]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Kir Kolyshkin <kir@openvz.org>
Tested-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

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