Lucid CVE-2010-4163: block: check for proper length of iov entries earlier in blk_rq_map_user_iov()

[Brad Figg]

On 02/18/2011 12:57 PM, Tim Gardner wrote:
> The following changes since commit 8c3a95c0fad82b89a1f8f89c74bfe9a8bb951072:
>    Brad Figg (1):
>          UBUNTU: Ubuntu-2.6.32-29.58
>
> are available in the git repository at:
>
>    git://kernel.ubuntu.com/rtg/ubuntu-lucid.git CVE-2010-4163
>
> Xiaotian Feng (1):
>        block: check for proper length of iov entries earlier in blk_rq_map_user_iov(), CVE-2010-4163
>
>   block/blk-map.c |    5 +++--
>   1 files changed, 3 insertions(+), 2 deletions(-)
>
>  From 6ca90f56c3a0b0f6b12dd2249c53d3071a111448 Mon Sep 17 00:00:00 2001
> From: Xiaotian Feng<dfeng at redhat.com>
> Date: Mon, 29 Nov 2010 10:03:55 +0100
> Subject: [PATCH] block: check for proper length of iov entries earlier in blk_rq_map_user_iov(), CVE-2010-4163
>
> BugLink: http://bugs.launchpad.net/bugs/721504
>
> CVE-2010-4163
>
> commit 9284bcf checks for proper length of iov entries in
> blk_rq_map_user_iov(). But if the map is unaligned, kernel
> will break out the loop without checking for the proper length.
> So we need to check the proper length before the unalign check.
>
> Signed-off-by: Xiaotian Feng<dfeng at redhat.com>
> Cc: stable at kernel.org
> Signed-off-by: Jens Axboe<jaxboe at fusionio.com>
> (cherry picked from commit 5478755616ae2ef1ce144dded589b62b2a50d575)
>
> Signed-off-by: Tim Gardner<tim.gardner at canonical.com>
> ---
>   block/blk-map.c |    5 +++--
>   1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-map.c b/block/blk-map.c
> index 30a7e51..749effa 100644
> --- a/block/blk-map.c
> +++ b/block/blk-map.c
> @@ -201,12 +201,13 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
>   	for (i = 0; i<  iov_count; i++) {
>   		unsigned long uaddr = (unsigned long)iov[i].iov_base;
>
> +		if (!iov[i].iov_len)
> +			return -EINVAL;
> +
>   		if (uaddr&  queue_dma_alignment(q)) {
>   			unaligned = 1;
>   			break;
>   		}
> -		if (!iov[i].iov_len)
> -			return -EINVAL;
>   	}
>
>   	if (unaligned || (q->dma_pad_mask&  len) || map_data)

Acked-by: Brad Figg <brad.figg at canonical.com>

-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com