From: Oleg Nesterov <oleg@tv-sign.ru>
Date: Wed, 30 Apr 2008 07:54:28 +0000 (-0700)
Subject: pids: sys_getsid: fix unsafe *pid usage, fix possible 0 instead of -ESRCH
X-Git-Tag: v2.6.26-rc1~163
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1dd768c0815334d2319d6377f0750ace075b6142;p=pandora-kernel.git

pids: sys_getsid: fix unsafe *pid usage, fix possible 0 instead of -ESRCH

1. sys_getsid() needs rcu_read_lock() to derive the session _nr, even if
   the task is current, otherwise we can race with another thread which
   does sys_setsid().

2. The task can exit between find_task_by_vpid() and task_session_vnr(),
   in that unlikely case sys_getsid() returns 0 instead of -ESRCH.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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