Patch "scsi: sg: only check for dxfer_len greater than 256M" has been added to the 4.12-stable tree

This is a note to let you know that I've just added the patch titled

scsi: sg: only check for dxfer_len greater than 256M

to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
scsi-sg-only-check-for-dxfer_len-greater-than-256m.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Johannes Thumshirn <[email protected]>
Date: Thu, 27 Jul 2017 09:11:26 +0200
Subject: scsi: sg: only check for dxfer_len greater than 256M

From: Johannes Thumshirn <[email protected]>

commit f930c7043663188429cd9b254e9d761edfc101ce upstream.

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.

request)

---
 drivers/scsi/sg.c |   25 +------------------------
 1 file changed, 1 insertion(+), 24 deletions(-)

@@ -751,29 +751,6 @@ sg_new_write(Sg_fd *sfp, struct file *fi
 	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_TO_DEV:
-	case SG_DXFER_FROM_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)

@@ -794,7 +771,7 @@ sg_common_write(Sg_fd * sfp, Sg_request
 			"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);

Patches currently in stable-queue which might be from [email protected] are

queue-4.12/scsi-sg-only-check-for-dxfer_len-greater-than-256m.patch