uglify kill_pid_info() to fix kill() vs exec() race
authorOleg Nesterov <oleg@tv-sign.ru>
Fri, 8 Feb 2008 12:19:18 +0000 (04:19 -0800)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Fri, 8 Feb 2008 17:22:28 +0000 (09:22 -0800)
commitd36174bc2bce0372693a9cfbdef8b2689c9982cb
treecdb327c68844f105a8ac8b732e862f24edc35f24
parentf374ada53bd1ca7c16d7607369fccc6769704956
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>
kernel/signal.c