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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Johannes Thumshirn <jthumshirn@suse.de>,
        Hannes Reinecke <hare@suse.com>,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.4 078/115] scsi: sg: check for valid direction
 before starting the request
Thread-Topic: [PATCH AUTOSEL for 4.4 078/115] scsi: sg: check for valid
 direction before starting the request
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Date:   Sat, 3 Mar 2018 22:31:35 +0000
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From: Johannes Thumshirn <jthumshirn@suse.de>

[ Upstream commit 28676d869bbb5257b5f14c0c95ad3af3a7019dd5 ]

Check for a valid direction before starting the request, otherwise we
risk running into an assertion in the scsi midlayer checking for valid
requests.

[mkp: fixed typo]

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Link: http://www.spinics.net/lists/linux-scsi/msg104400.html
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Hannes Reinecke <hare@suse.com>
Tested-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/scsi/sg.c | 46 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 34 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 0f0ff75755e0..27f92f4ea6bc 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -674,18 +674,14 @@ sg_write(struct file *filp, const char __user *buf, s=
ize_t count, loff_t * ppos)
 	 * is a non-zero input_size, so emit a warning.
 	 */
 	if (hp->dxfer_direction =3D=3D SG_DXFER_TO_FROM_DEV) {
-		static char cmd[TASK_COMM_LEN];
-		if (strcmp(current->comm, cmd)) {
-			printk_ratelimited(KERN_WARNING
-					   "sg_write: data in/out %d/%d bytes "
-					   "for SCSI command 0x%x-- guessing "
-					   "data in;\n   program %s not setting "
-					   "count and/or reply_len properly\n",
-					   old_hdr.reply_len - (int)SZ_SG_HEADER,
-					   input_size, (unsigned int) cmnd[0],
-					   current->comm);
-			strcpy(cmd, current->comm);
-		}
+		printk_ratelimited(KERN_WARNING
+				   "sg_write: data in/out %d/%d bytes "
+				   "for SCSI command 0x%x-- guessing "
+				   "data in;\n   program %s not setting "
+				   "count and/or reply_len properly\n",
+				   old_hdr.reply_len - (int)SZ_SG_HEADER,
+				   input_size, (unsigned int) cmnd[0],
+				   current->comm);
 	}
 	k =3D sg_common_write(sfp, srp, cmnd, sfp->timeout, blocking);
 	return (k < 0) ? k : count;
@@ -764,6 +760,29 @@ sg_new_write(Sg_fd *sfp, struct file *file, const char=
 __user *buf,
 	return count;
 }
=20
+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 =3D=3D 0)
+			return false;
+		return true;
+	case SG_DXFER_UNKNOWN:
+		if ((!hp->dxferp && hp->dxfer_len) ||
+		    (hp->dxferp && hp->dxfer_len =3D=3D 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)
@@ -784,6 +803,9 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
 			"sg_common_write:  scsi opcode=3D0x%02x, cmd_size=3D%d\n",
 			(int) cmnd[0], (int) hp->cmd_len));
=20
+	if (!sg_is_valid_dxfer(hp))
+		return -EINVAL;
+
 	k =3D sg_start_req(srp, cmnd);
 	if (k) {
 		SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sfp->parentdp,
--=20
2.14.1