linux-kernel - [PATCH] posix-timer: don't call idr

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20130220210116.GD3570@htj.dyndns.org>
Date:	Wed, 20 Feb 2013 13:01:16 -0800
From:	Tejun Heo <tj@...nel.org>
To:	akpm@...ux-foundation.org, Sasha Levin <sasha.levin@...cle.com>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH] posix-timer: don't call idr_find() w/ negative ID

Recent idr updates make idr_find() trigger WARN_ON_ONCE() before
returning NULL when a negative ID is specified.  Apparently,
posix-timer::__lock_timer() was depending on idr_find() returning NULL
on negative ID, thus triggering the new WARN_ON_ONCE().  Make
__lock_timer() first check whether @timer_id is negative and return
NULL without invoking idr_find() if so.

Note that the previous code was theoretically broken.  idr_find()
masked off the sign bit before performing lookup and if the matching
IDs were in use, it would have returned pointer for the incorrect
entry.

Signed-off-by: Tejun Heo <tj@...nel.org>
Reported-by: Sasha Levin <sasha.levin@...cle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
---
Sasha, can you please test whether this makes the warning go away?

Thanks.

 kernel/posix-timers.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index b51bb08..92465f9 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -637,6 +637,9 @@ static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
 {
 	struct k_itimer *timr;

+	if ((int)timer_id < 0)
+		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@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/