Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756610Ab3CDDnw (ORCPT ); Sun, 3 Mar 2013 22:43:52 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:32926 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756387Ab3CDDnu (ORCPT ); Sun, 3 Mar 2013 22:43:50 -0500 Message-Id: <20130304033716.283848524@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 04 Mar 2013 03:38:35 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, Tejun Heo , Sasha Levin , Thomas Gleixner Subject: [ 088/153] posix-timer: Dont call idr_find() with out-of-range ID In-Reply-To: <20130304033707.648729212@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:a11:96ff:fec6:70c4 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2110 Lines: 59 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tejun Heo commit e182bb38d7db7494fa5dcd82da17fe0dedf60ecf upstream. When idr_find() was fed a negative ID, it used to look up the ID ignoring the sign bit before recent ("idr: remove MAX_IDR_MASK and move left MAX_IDR_* into idr.c") patch. Now a negative ID triggers a WARN_ON_ONCE(). __lock_timer() feeds timer_id from userland directly to idr_find() without sanitizing it which can trigger the above malfunctions. Add a range check on @timer_id before invoking idr_find() in __lock_timer(). While timer_t is defined as int by all archs at the moment, Andrew worries that it may be defined as a larger type later on. Make the test cover larger integers too so that it at least is guaranteed to not return the wrong timer. Note that WARN_ON_ONCE() in idr_find() on id < 0 is transitional precaution while moving away from ignoring MSB. Once it's gone we can remove the guard as long as timer_t isn't larger than int. Signed-off-by: Tejun Heo nnn Reported-by: Sasha Levin Cc: Andrew Morton Link: http://lkml.kernel.org/r/20130220232412.GL3570@htj.dyndns.org Signed-off-by: Thomas Gleixner Signed-off-by: Ben Hutchings --- kernel/posix-timers.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -639,6 +639,13 @@ static struct k_itimer *__lock_timer(tim { struct k_itimer *timr; + /* + * timer_t could be any type >= int and we want to make sure any + * @timer_id outside positive int range fails lookup. + */ + if ((unsigned long long)timer_id > INT_MAX) + return NULL; + rcu_read_lock(); timr = idr_find(&posix_timers_id, (int)timer_id); if (timr) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/