[dm-devel] [PATCH v2] dm: Check for device sector overflow if CONFIG_LBDAF is not set

[Mikulas Patocka]

On Wed, 7 Nov 2018, Milan Broz wrote:

> Reference to a device in device-mapper table contains offset in sectors.
> 
> If the sector_t is 32bit integer (CONFIG_LBDAF is not set), then
> several device-mapper targets can overflow this offset and validity
> check is then performed on a wrong offset and a wrong table is activated.
> 
> See for example (on 32bit without CONFIG_LBDAF) this overflow:
> 
>   # dmsetup create test --table "0 2048 linear /dev/sdg 4294967297"
>   # dmsetup table test
>   0 2048 linear 8:96 1
> 
> This patch adds explicit check for overflow if the offset is sector_t type.
> 
> Signed-off-by: Milan Broz <gmazyland at gmail.com>

Reviewed-by: Mikulas Patocka <mpatocka at redhat.com>

> ---
>  drivers/md/dm-crypt.c    | 2 +-
>  drivers/md/dm-delay.c    | 2 +-
>  drivers/md/dm-flakey.c   | 2 +-
>  drivers/md/dm-linear.c   | 2 +-
>  drivers/md/dm-raid1.c    | 3 ++-
>  drivers/md/dm-unstripe.c | 2 +-
>  6 files changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
> index 49be7a6a2e81..a41fe7975dc6 100644
> --- a/drivers/md/dm-crypt.c
> +++ b/drivers/md/dm-crypt.c
> @@ -2781,7 +2781,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
>  	}
>  
>  	ret = -EINVAL;
> -	if (sscanf(argv[4], "%llu%c", &tmpll, &dummy) != 1) {
> +	if (sscanf(argv[4], "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
>  		ti->error = "Invalid device sector";
>  		goto bad;
>  	}
> diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
> index 2fb7bb4304ad..fddffe251bf6 100644
> --- a/drivers/md/dm-delay.c
> +++ b/drivers/md/dm-delay.c
> @@ -141,7 +141,7 @@ static int delay_class_ctr(struct dm_target *ti, struct delay_class *c, char **a
>  	unsigned long long tmpll;
>  	char dummy;
>  
> -	if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1) {
> +	if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
>  		ti->error = "Invalid device sector";
>  		return -EINVAL;
>  	}
> diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
> index 3cb97fa4c11d..8261aa8c7fe1 100644
> --- a/drivers/md/dm-flakey.c
> +++ b/drivers/md/dm-flakey.c
> @@ -213,7 +213,7 @@ static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
>  	devname = dm_shift_arg(&as);
>  
>  	r = -EINVAL;
> -	if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
> +	if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
>  		ti->error = "Invalid device sector";
>  		goto bad;
>  	}
> diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
> index 8d7ddee6ac4d..ad980a38fb1e 100644
> --- a/drivers/md/dm-linear.c
> +++ b/drivers/md/dm-linear.c
> @@ -45,7 +45,7 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
>  	}
>  
>  	ret = -EINVAL;
> -	if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) {
> +	if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1 || tmp != (sector_t)tmp) {
>  		ti->error = "Invalid device sector";
>  		goto bad;
>  	}
> diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
> index 79eab1071ec2..5a51151f680d 100644
> --- a/drivers/md/dm-raid1.c
> +++ b/drivers/md/dm-raid1.c
> @@ -943,7 +943,8 @@ static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
>  	char dummy;
>  	int ret;
>  
> -	if (sscanf(argv[1], "%llu%c", &offset, &dummy) != 1) {
> +	if (sscanf(argv[1], "%llu%c", &offset, &dummy) != 1 ||
> +	    offset != (sector_t)offset) {
>  		ti->error = "Invalid offset";
>  		return -EINVAL;
>  	}
> diff --git a/drivers/md/dm-unstripe.c b/drivers/md/dm-unstripe.c
> index 954b7ab4e684..e673dacf6418 100644
> --- a/drivers/md/dm-unstripe.c
> +++ b/drivers/md/dm-unstripe.c
> @@ -78,7 +78,7 @@ static int unstripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
>  		goto err;
>  	}
>  
> -	if (sscanf(argv[4], "%llu%c", &start, &dummy) != 1) {
> +	if (sscanf(argv[4], "%llu%c", &start, &dummy) != 1 || start != (sector_t)start) {
>  		ti->error = "Invalid striped device offset";
>  		goto err;
>  	}
> -- 
> 2.19.1
>