From: Andrew Vagin <avagin@openvz.org>
Date: Mon, 17 Sep 2012 21:09:12 +0000 (-0700)
Subject: pid-namespace: limit value of ns_last_pid to (0, max_pid)
X-Git-Tag: v3.6-rc7~34^2~4
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=579035dc5ddd6d48fd8529e7358b03d911ab9d8a;p=pandora-kernel.git

pid-namespace: limit value of ns_last_pid to (0, max_pid)

The kernel doesn't check the pid for negative values, so if you try to
write -2 to /proc/sys/kernel/ns_last_pid, you will get a kernel panic.

The crash happens because the next pid is -1, and alloc_pidmap() will
try to access to a nonexistent pidmap.

  map = &pid_ns->pidmap[pid/BITS_PER_PAGE];

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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