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

[Leann Ogasawara]

On Mon, 2011-06-13 at 15:03 +0100, 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>

Acked-by: Leann Ogasawara <leann.ogasawara 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))
> -- 
> 1.7.4.1
> 
>