[PATCH] scsi: sg: only check for dxfer_len greater than 256M

[PATCH] scsi: sg: only check for dxfer_len greater than 256M

[Johannes Thumshirn]

Don't make any assumptions on the sg_io_hdr_t::dxfer_direction or the
sg_io_hdr_t::dxferp in order to determine if it is a valid request. The
only way we can check for bad requests is by checking if the length exceeds
256M.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Fixes: 28676d869bbb (scsi: sg: check for valid direction before starting the
request)
Reported-by: Jason L Tibbitts III <tibbs@math.uh.edu>
Tested-by: Jason L Tibbitts III <tibbs@math.uh.edu>
Suggested-by: Doug Gilbert <dgilbert@interlog.com>
Cc: Doug Gilbert <dgilbert@interlog.com>
Cc: <stable@vger.kernel.org>
---
 drivers/scsi/sg.c | 31 +------------------------------
 1 file changed, 1 insertion(+), 30 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 4fe606b000b4..d7ff71e0c85c 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -751,35 +751,6 @@ sg_new_write(Sg_fd *sfp, struct file *file, const char __user *buf,
 	return count;
 }
 
-static bool sg_is_valid_dxfer(sg_io_hdr_t *hp)
-{
-	switch (hp->dxfer_direction) {
-	case SG_DXFER_NONE:
-		if (hp->dxferp || hp->dxfer_len > 0)
-			return false;
-		return true;
-	case SG_DXFER_FROM_DEV:
-		/*
-		 * for SG_DXFER_FROM_DEV we always set dxfer_len to > 0. dxferp
-		 * can either be NULL or != NULL so there's no point in checking
-		 * it either. So just return true.
-		 */
-		return true;
-	case SG_DXFER_TO_DEV:
-	case SG_DXFER_TO_FROM_DEV:
-		if (!hp->dxferp || hp->dxfer_len == 0)
-			return false;
-		return true;
-	case SG_DXFER_UNKNOWN:
-		if ((!hp->dxferp && hp->dxfer_len) ||
-		    (hp->dxferp && hp->dxfer_len == 0))
-			return false;
-		return true;
-	default:
-		return false;
-	}
-}
-
 static int
 sg_common_write(Sg_fd * sfp, Sg_request * srp,
 		unsigned char *cmnd, int timeout, int blocking)
@@ -800,7 +771,7 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
 			"sg_common_write:  scsi opcode=0x%02x, cmd_size=%d\n",
 			(int) cmnd[0], (int) hp->cmd_len));
 
-	if (!sg_is_valid_dxfer(hp))
+	if (hp->dxfer_len >= SZ_256M)
 		return -EINVAL;
 
 	k = sg_start_req(srp, cmnd);
-- 
2.12.3

Re: [PATCH] scsi: sg: only check for dxfer_len greater than 256M

[Hannes Reinecke]

On 07/27/2017 09:11 AM, Johannes Thumshirn wrote:
> Don't make any assumptions on the sg_io_hdr_t::dxfer_direction or the
> sg_io_hdr_t::dxferp in order to determine if it is a valid request. The
> only way we can check for bad requests is by checking if the length exceeds
> 256M.
> 
> Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
> Fixes: 28676d869bbb (scsi: sg: check for valid direction before starting the
> request)
> Reported-by: Jason L Tibbitts III <tibbs@math.uh.edu>
> Tested-by: Jason L Tibbitts III <tibbs@math.uh.edu>
> Suggested-by: Doug Gilbert <dgilbert@interlog.com>
> Cc: Doug Gilbert <dgilbert@interlog.com>
> Cc: <stable@vger.kernel.org>
> ---
>  drivers/scsi/sg.c | 31 +------------------------------
>  1 file changed, 1 insertion(+), 30 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)

Re: [PATCH] scsi: sg: only check for dxfer_len greater than 256M

[Martin K. Petersen]

Johannes,

> Don't make any assumptions on the sg_io_hdr_t::dxfer_direction or the
> sg_io_hdr_t::dxferp in order to determine if it is a valid
> request. The only way we can check for bad requests is by checking if
> the length exceeds 256M.

Applied to 4.13/scsi-fixes. Thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH] scsi: sg: only check for dxfer_len greater than 256M

[Jason L Tibbitts III]

>>>>> "MKP" == Martin K Petersen <martin.petersen@oracle.com> writes:

MKP> Applied to 4.13/scsi-fixes. Thanks!

My thanks as well to everyone who helped in getting this fixed.

 - J<