From: Sasha Levin <sasha.levin@oracle.com>
To: Tejun Heo <tj@kernel.org>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] posix-timer: don't call idr_find() w/ negative ID
Date: Wed, 20 Feb 2013 16:32:22 -0500 [thread overview]
Message-ID: <512540E6.7070302@oracle.com> (raw)
In-Reply-To: <20130220210116.GD3570@htj.dyndns.org>
On 02/20/2013 04:01 PM, Tejun Heo wrote:
> 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@kernel.org>
> Reported-by: Sasha Levin <sasha.levin@oracle.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> ---
> Sasha, can you please test whether this makes the warning go away?
Looks like it did.
Thanks,
Sasha
next prev parent reply other threads:[~2013-02-20 21:32 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-20 18:44 [PATCH] idr: prevent NULL deref on lookups before insertions Sasha Levin
2013-02-20 18:45 ` Tejun Heo
2013-02-20 19:23 ` Sasha Levin
2013-02-20 21:01 ` [PATCH] posix-timer: don't call idr_find() w/ negative ID Tejun Heo
2013-02-20 21:23 ` Andrew Morton
2013-02-20 21:37 ` Tejun Heo
2013-02-20 22:05 ` Andrew Morton
2013-02-20 22:08 ` Tejun Heo
2013-02-20 22:40 ` [PATCH] posix-timer: don't call idr_find() w/ out-of-range ID Tejun Heo
2013-02-20 23:01 ` Thomas Gleixner
2013-02-20 23:07 ` Tejun Heo
2013-02-20 23:11 ` Thomas Gleixner
2013-02-20 23:24 ` [PATCH UPDATED] " Tejun Heo
2013-02-20 23:35 ` [PATCH] idr: explain WARN_ON_ONCE() on negative IDs " Tejun Heo
2013-02-21 9:10 ` Thomas Gleixner
2013-02-21 16:38 ` [tip:timers/urgent] posix-timer: Don't call idr_find() with " tip-bot for Tejun Heo
2013-02-20 22:10 ` [PATCH] posix-timer: don't call idr_find() w/ negative ID Sasha Levin
2013-02-20 22:12 ` Tejun Heo
2013-02-20 22:15 ` Sasha Levin
2013-02-20 22:20 ` Tejun Heo
2013-02-20 23:09 ` Thomas Gleixner
2013-02-20 21:32 ` Sasha Levin [this message]
2013-02-20 21:38 ` Thomas Gleixner
2013-02-20 21:43 ` Tejun Heo
2013-02-20 21:47 ` Thomas Gleixner
2013-02-20 21:50 ` Tejun Heo
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