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From: Jens Axboe <axboe@kernel.dk>
To: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Meelis Roos <mroos@linux.ee>
Cc: Linux Kernel list <linux-kernel@vger.kernel.org>,
	linux-ide@vger.kernel.org, linux-block@vger.kernel.org,
	Tejun Heo <tj@kernel.org>
Subject: Re: UBSAN: Undefined behaviour in block/blk-mq.c:1459:27 with pata_amd
Date: Mon, 16 May 2016 09:55:31 -0600	[thread overview]
Message-ID: <5739ED73.4020009@kernel.dk> (raw)
In-Reply-To: <22191628.vH7YQZ1hRO@amdc1976>

On 05/13/2016 09:31 AM, Bartlomiej Zolnierkiewicz wrote:
> Does the patch below help?
>
> From: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> Subject: [PATCH] blk-mq: fix undefined behaviour in order_to_size()
>
> When this_order variable in blk_mq_init_rq_map() becomes zero
> the code incorrectly decrements the variable and passes the result
> to order_to_size() helper causing undefined behaviour:
>
>   UBSAN: Undefined behaviour in block/blk-mq.c:1459:27
>   shift exponent 4294967295 is too large for 32-bit type 'unsigned int'
>   CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.6.0-rc6-00072-g33656a1 #22
>
> Fix the code by checking this_order variable for not having the zero
> value first.

Thanks Bart, added for 4.7.

-- 
Jens Axboe

  parent reply	other threads:[~2016-05-16 15:55 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-12 16:05 UBSAN: Undefined behaviour in block/blk-mq.c:1459:27 with pata_amd Meelis Roos
2016-05-13 15:31 ` Bartlomiej Zolnierkiewicz
2016-05-14  9:05   ` Meelis Roos
2016-05-16 15:55   ` Jens Axboe [this message]
2016-05-18  6:59   ` Meelis Roos

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