linux-kernel - Re: [PATCH] blk-mq: fix double-free in error path

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Message-ID: <54DB86C5.4090607@kernel.dk>
Date:	Wed, 11 Feb 2015 09:43:49 -0700
From:	Jens Axboe <axboe@...nel.dk>
To:	Tony Battersby <tonyb@...ernetics.com>, linux-scsi@...r.kernel.org,
	"James E.J. Bottomley" <JBottomley@...allels.com>,
	Christoph Hellwig <hch@...radead.org>
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] blk-mq: fix double-free in error path

On 02/11/2015 09:32 AM, Tony Battersby wrote:
> If the allocation of bt->bs fails, then bt->map can be freed twice, once
> in blk_mq_init_bitmap_tags() -> bt_alloc(), and once in
> blk_mq_init_bitmap_tags() -> bt_free().  Fix by setting the pointer to
> NULL after the first free.
>
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Tony Battersby <tonyb@...ernetics.com>
> ---
>
> For inclusion in kernel 3.20.
>
> --- linux-3.19.0/block/blk-mq-tag.c.orig	2015-02-08 21:54:22.000000000 -0500
> +++ linux-3.19.0/block/blk-mq-tag.c	2015-02-10 09:42:38.000000000 -0500
> @@ -509,6 +509,7 @@ static int bt_alloc(struct blk_mq_bitmap
>   	bt->bs = kzalloc(BT_WAIT_QUEUES * sizeof(*bt->bs), GFP_KERNEL);
>   	if (!bt->bs) {
>   		kfree(bt->map);
> +		bt->map = NULL;
>   		return -ENOMEM;
>   	}

Thanks Tony, applied.


-- 
Jens Axboe

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