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From: Patrick McHardy <kaber@trash.net>
To: Jan Engelhardt <jengelh@medozas.de>
Cc: Adam Nielsen <a.nielsen@shikadi.net>,
	Netfilter Developer Mailing List
	<netfilter-devel@vger.kernel.org>
Subject: Re: [PATCH v2] Add refcounts to LED target
Date: Wed, 07 Apr 2010 18:15:19 +0200	[thread overview]
Message-ID: <4BBCAF97.6040806@trash.net> (raw)
In-Reply-To: <alpine.LSU.2.01.1004041327160.22215@obet.zrqbmnf.qr>

Jan Engelhardt wrote:
> On Sunday 2010-03-28 03:25, Adam Nielsen wrote:
> 
>> Add reference counting to the LED target so that multiple targets sharing the
>> same trigger don't cause any problems.
> 
> I also noticed one another thing: you don't increase the refcount while 
> xt_led_mutex is held. That means it is theoretically possible that you 
> do a lookup, then a destructor runs and frees the object, leading to 
> ++ledinternal->refcnt dereference an illegal ledinternal.

Indeed, I also noticed this. Basically, you need to make sure that

- the lookup and refcnt increase is atomic,
- the refcnt decrease and list deletion is atomic
- the lookup and list insertion is atomic (in case no trigger exists)

The remaining parts look fine to me, thanks.

  reply	other threads:[~2010-04-07 16:15 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-24  1:46 Avoiding multiple calls to xt_target.checkentry Adam Nielsen
2009-05-24  7:34 ` Jan Engelhardt
2009-05-27 23:07   ` Adam Nielsen
2009-05-28 21:06     ` Jan Engelhardt
2009-06-03  9:25     ` Patrick McHardy
2009-06-03 11:03       ` Adam Nielsen
2009-11-05 15:00         ` Patrick McHardy
2009-11-05 18:40           ` Jan Engelhardt
2009-11-05 18:43             ` Patrick McHardy
2009-11-05 22:04           ` Adam Nielsen
2009-11-06 14:56             ` Patrick McHardy
2009-11-29  1:43               ` [PATCH] Add refcounts to LED target Adam Nielsen
2009-11-29 10:12                 ` Jan Engelhardt
2009-11-29 11:33                   ` Adam Nielsen
2009-11-29 15:49                     ` Jan Engelhardt
2009-12-01 10:05                       ` Patrick McHardy
2009-12-06 10:09                         ` Adam Nielsen
2009-12-06 13:24                           ` Patrick McHardy
2010-03-25 14:01                             ` Patrick McHardy
2010-03-25 14:05                               ` Jan Engelhardt
2010-03-25 14:08                                 ` Patrick McHardy
2010-03-27  4:05                                   ` Adam Nielsen
2010-03-27 11:15                                     ` Jan Engelhardt
2010-03-27 11:39                                       ` Adam Nielsen
2010-03-27 11:55                                         ` Jan Engelhardt
2010-03-28  1:25                                           ` [PATCH v2] " Adam Nielsen
2010-04-04 11:30                                             ` Jan Engelhardt
2010-04-07 16:15                                               ` Patrick McHardy [this message]
2010-04-08  3:03                                                 ` [PATCH v3] " Adam Nielsen
2010-04-08 11:33                                                   ` Patrick McHardy
2010-04-08 12:45                                                     ` Jan Engelhardt
2010-04-08 12:57                                                       ` Patrick McHardy
2010-04-08 23:06                                                         ` [PATCH v4] " Adam Nielsen
2010-04-09 14:52                                                           ` Patrick McHardy
2010-04-08 21:07                                                   ` [PATCH v3] " Florian Westphal
2010-04-08 22:45                                                     ` Adam Nielsen
2010-03-27 18:42                                     ` [PATCH] " Jan Engelhardt
2010-03-28  1:58                                       ` Adam Nielsen
2010-04-04 11:59                                         ` Jan Engelhardt
2010-04-08  3:15                                           ` input-layer LEDs as LED-class devices (was: Add refcounts to LED target) Adam Nielsen
2010-04-08  8:03                                             ` Jan Engelhardt

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