[Acked]Re: [hardy, lucid/fsl-imx51 CVE 1/1] Fix corrupted OSF partition table parsing

[Brad Figg]

On 06/13/2011 03:03 PM, Andy Whitcroft wrote:
> From: Timo Warns<Warns at pre-sense.de>
>
> commit 1eafbfeb7bdf59cfe173304c76188f3fd5f1fd05 upstream.
>
> The kernel automatically evaluates partition tables of storage devices.
> The code for evaluating OSF partitions contains a bug that leaks data
> from kernel heap memory to userspace for certain corrupted OSF
> partitions.
>
> In more detail:
>
>    for (i = 0 ; i<  le16_to_cpu(label->d_npartitions); i++, partition++) {
>
> iterates from 0 to d_npartitions - 1, where d_npartitions is read from
> the partition table without validation and partition is a pointer to an
> array of at most 8 d_partitions.
>
> Add the proper and obvious validation.
>
> Signed-off-by: Timo Warns<warns at pre-sense.de>
> Cc: stable at kernel.org
> [ Changed the patch trivially to not repeat the whole le16_to_cpu()
>    thing, and to use an explicit constant for the magic value '8' ]
> Signed-off-by: Linus Torvalds<torvalds at linux-foundation.org>
> Signed-off-by: Greg Kroah-Hartman<gregkh at suse.de>
> Signed-off-by: Stefan Bader<stefan.bader at canonical.com>
> Signed-off-by: Tim Gardner<tim.gardner at canonical.com>
>
> (backported from 1eafbfeb7bdf59cfe173304c76188f3fd5f1fd05 upstream)
> CVE-2011-1163
> BugLink: http://bugs.launchpad.net/bugs/796606
> Signed-off-by: Andy Whitcroft<apw at canonical.com>
> ---
>   fs/partitions/osf.c |   12 ++++++++++--
>   1 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/fs/partitions/osf.c b/fs/partitions/osf.c
> index c05c17bc..6e0825e 100644
> --- a/fs/partitions/osf.c
> +++ b/fs/partitions/osf.c
> @@ -10,10 +10,13 @@
>   #include "check.h"
>   #include "osf.h"
>
> +#define MAX_OSF_PARTITIONS 8
> +
>   int osf_partition(struct parsed_partitions *state, struct block_device *bdev)
>   {
>   	int i;
>   	int slot = 1;
> +	unsigned int npartitions;
>   	Sector sect;
>   	unsigned char *data;
>   	struct disklabel {
> @@ -45,7 +48,7 @@ int osf_partition(struct parsed_partitions *state, struct block_device *bdev)
>   			u8  p_fstype;
>   			u8  p_frag;
>   			__le16 p_cpg;
> -		} d_partitions[8];
> +		} d_partitions[MAX_OSF_PARTITIONS];
>   	} * label;
>   	struct d_partition * partition;
>
> @@ -63,7 +66,12 @@ int osf_partition(struct parsed_partitions *state, struct block_device *bdev)
>   		put_dev_sector(sect);
>   		return 0;
>   	}
> -	for (i = 0 ; i<  le16_to_cpu(label->d_npartitions); i++, partition++) {
> +	npartitions = le16_to_cpu(label->d_npartitions);
> +	if (npartitions>  MAX_OSF_PARTITIONS) {
> +		put_dev_sector(sect);
> +		return 0;
> +	}
> +	for (i = 0 ; i<  npartitions; i++, partition++) {
>   		if (slot == state->limit)
>   		        break;
>   		if (le32_to_cpu(partition->p_size))

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