From: Tejun Heo <tj@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org, Sasha Levin <sasha.levin@oracle.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] posix-timer: don't call idr_find() w/ negative ID
Date: Wed, 20 Feb 2013 13:43:46 -0800 [thread overview]
Message-ID: <20130220214346.GF3570@htj.dyndns.org> (raw)
In-Reply-To: <alpine.LFD.2.02.1302202208470.22263@ionos>
Hey, Thomas.
On Wed, Feb 20, 2013 at 10:38:36PM +0100, Thomas Gleixner wrote:
> I can grumpily accept the patch below as a quick hack fix, which can
> go to stable as well, but not with such a patently misleading
> changelog.
>
> The changelog wants to document, that this is not a proper fix at all
> and just a quick hack which can be nonintrusively applied to stable.
I'm not sure about what type timer_t can be but if it can actually be
u64 as Andrew suggests, we probably want a different test guarding it.
> > 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.
>
> Brilliant code that. What's the purpose of having the idr id as an
> "int" and then masking off the sign bit instead of simply refusing
> negative id values in the idr code itself or simply making the id
> "unsigned int" ?
Beats me. The code has been like that since the beginning. One of
the many oddities of idr implementation. Patch to remove MAX_IDR_MASK
is already queued in -mm w/ other idr updates.
Thanks.
--
tejun
next prev parent reply other threads:[~2013-02-20 21:43 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
2013-02-20 21:38 ` Thomas Gleixner
2013-02-20 21:43 ` Tejun Heo [this message]
2013-02-20 21:47 ` Thomas Gleixner
2013-02-20 21:50 ` Tejun Heo
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