From: Stanislav Kinsbursky <skinsbursky@parallels.com>
Date: Tue, 27 Nov 2012 00:29:42 +0000 (-0800)
Subject: proc: check vma->vm_file before dereferencing
X-Git-Tag: v3.7-rc8~27^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=05f564849d49499ced97913a0914b5950577d07d;p=pandora-kernel.git

proc: check vma->vm_file before dereferencing

Commit 7b540d0646ce ("proc_map_files_readdir(): don't bother with
grabbing files") switched proc_map_files_readdir() to use @f_mode
directly instead of grabbing @file reference, but same time the test for
@vm_file presence was lost leading to nil dereference.  The patch brings
the test back.

The all proc_map_files feature is CONFIG_CHECKPOINT_RESTORE wrapped
(which is set to 'n' by default) so the bug doesn't affect regular
kernels.

The regression is 3.7-rc1 only as far as I can tell.

[gorcunov@openvz.org: provided changelog]
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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