linux-kernel - [PATCH 3.16 37/61] scsi: sg: check for valid direction before starting the request

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Message-ID: <lsq.1591725832.9336726@decadent.org.uk>
Date:   Tue, 09 Jun 2020 19:04:28 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Hannes Reinecke" <hare@...e.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Sasha Levin" <alexander.levin@...rosoft.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "Dmitry Vyukov" <dvyukov@...gle.com>,
        "Johannes Thumshirn" <jthumshirn@...e.de>,
        "Christoph Hellwig" <hch@....de>
Subject: [PATCH 3.16 37/61] scsi: sg: check for valid direction before
 starting the request

3.16.85-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Thumshirn <jthumshirn@...e.de>

commit 28676d869bbb5257b5f14c0c95ad3af3a7019dd5 upstream.

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@...e.de>
Link: http://www.spinics.net/lists/linux-scsi/msg104400.html
Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Signed-off-by: Hannes Reinecke <hare@...e.com>
Tested-by: Johannes Thumshirn <jthumshirn@...e.de>
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/scsi/sg.c | 46 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 34 insertions(+), 12 deletions(-)

--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -701,18 +701,14 @@ sg_write(struct file *filp, const char _
 	 * is a non-zero input_size, so emit a warning.
 	 */
 	if (hp->dxfer_direction == 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 = sg_common_write(sfp, srp, cmnd, sfp->timeout, blocking);
 	return (k < 0) ? k : count;
@@ -790,6 +786,29 @@ 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)
@@ -809,6 +828,9 @@ sg_common_write(Sg_fd * sfp, Sg_request
 	SCSI_LOG_TIMEOUT(4, printk("sg_common_write:  scsi opcode=0x%02x, cmd_size=%d\n",
 			  (int) cmnd[0], (int) hp->cmd_len));
 
+	if (!sg_is_valid_dxfer(hp))
+		return -EINVAL;
+
 	k = sg_start_req(srp, cmnd);
 	if (k) {
 		SCSI_LOG_TIMEOUT(1, printk("sg_common_write: start_req err=%d\n", k));