Hardy CVE, bio: take care not overflow page count when mapping/copying user data, CVE-2010-4162

[Brad Figg]

On 02/18/2011 12:06 PM, Tim Gardner wrote:
> The following changes since commit 0b2f210442dd2ca2c184c1451f5d41fa37e7c60b:
>    Brad Figg (1):
>          UBUNTU: Ubuntu-2.6.24-28.86
>
> are available in the git repository at:
>
>    git://kernel.ubuntu.com/rtg/ubuntu-hardy.git CVE-2010-4162
>
> Tim Gardner (1):
>        bio: take care not overflow page count when mapping/copying user data, CVE-2010-4162
>
>   fs/bio.c |    6 ++++++
>   1 files changed, 6 insertions(+), 0 deletions(-)
>
>  From 3034d11a31600265b7286ae11e770946b7650a0c Mon Sep 17 00:00:00 2001
> From: Tim Gardner<tim.gardner at canonical.com>
> Date: Fri, 18 Feb 2011 12:49:29 -0700
> Subject: [PATCH] bio: take care not overflow page count when mapping/copying user data, CVE-2010-4162
>
> BugLink: http://bugs.launchpad.net/bugs/721441
>
> CVE-2010-4162
>
> backported from commit cb4644cac4a2797afc847e6c92736664d4b0ea34 upstream.
>
> If the iovec is being set up in a way that causes uaddr + PAGE_SIZE
> to overflow, we could end up attempting to map a huge number of
> pages. Check for this invalid input type.
>
> Reported-by: Dan Rosenberg<drosenberg at vsecurity.com>
> Signed-off-by: Jens Axboe<jaxboe at fusionio.com>
> Signed-off-by: Greg Kroah-Hartman<gregkh at suse.de>
> Signed-off-by: Tim Gardner<tim.gardner at canonical.com>
> ---
>   fs/bio.c |    6 ++++++
>   1 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/fs/bio.c b/fs/bio.c
> index d59ddbf..2c8224c 100644
> --- a/fs/bio.c
> +++ b/fs/bio.c
> @@ -609,6 +609,12 @@ static struct bio *__bio_map_user_iov(struct request_queue *q,
>   		unsigned long end = (uaddr + len + PAGE_SIZE - 1)>>  PAGE_SHIFT;
>   		unsigned long start = uaddr>>  PAGE_SHIFT;
>
> +		/*
> +		 * Overflow, abort
> +		 */
> +		if (end<  start)
> +			return ERR_PTR(-EINVAL);
> +
>   		nr_pages += end - start;
>   		/*
>   		 * buffer must be aligned to at least hardsector size for now

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

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