linux-kernel - Re: [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]

Date:	Wed, 20 Feb 2013 13:43:46 -0800
From:	Tejun Heo <tj@...nel.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	akpm@...ux-foundation.org, Sasha Levin <sasha.levin@...cle.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] posix-timer: don't call idr_find() w/ negative ID

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
--
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/