From: Oleg Nesterov <oleg@tv-sign.ru>
Date: Fri, 8 Feb 2008 12:19:18 +0000 (-0800)
Subject: uglify kill_pid_info() to fix kill() vs exec() race
X-Git-Tag: v2.6.25-rc1~208
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d36174bc2bce0372693a9cfbdef8b2689c9982cb;p=pandora-kernel.git

uglify kill_pid_info() to fix kill() vs exec() race

kill_pid_info()->pid_task() could be the old leader of the execing process.
In that case it is possible that the leader will be released before we take
siglock. This means that kill_pid_info() (and thus sys_kill()) can return a
false -ESRCH.

Change the code to retry when lock_task_sighand() fails. The endless loop is
not possible, __exit_signal() both clears ->sighand and does detach_pid().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
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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