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

[Jens Axboe <axboe@kernel.dk>]

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@vger.kernel.org>
> Signed-off-by: Tony Battersby <tonyb@cybernetics.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