patch "USB: serial: digi_acceleport: fix OOB data sanity check" added to usb-testing

patch "USB: serial: digi_acceleport: fix OOB data sanity check" added to usb-testing

[gregkh]

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

    USB: serial: digi_acceleport: fix OOB data sanity check

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-testing branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will be merged to the usb-next branch sometime soon,
after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.


>From 2d380889215fe20b8523345649dee0579821800c Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Tue, 31 Jan 2017 17:17:27 +0100
Subject: USB: serial: digi_acceleport: fix OOB data sanity check

Make sure to check for short transfers to avoid underflow in a loop
condition when parsing the receive buffer.

Also fix an off-by-one error in the incomplete sanity check which could
lead to invalid data being parsed.

Fixes: 8c209e6782ca ("USB: make actual_length in struct urb field u32")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>	# v2.6.30
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/digi_acceleport.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/digi_acceleport.c b/drivers/usb/serial/digi_acceleport.c
index 6a1df9e824ca..3b610f1e3f7c 100644
--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -1482,16 +1482,20 @@ static int digi_read_oob_callback(struct urb *urb)
 	struct usb_serial *serial = port->serial;
 	struct tty_struct *tty;
 	struct digi_port *priv = usb_get_serial_port_data(port);
+	unsigned char *buf = urb->transfer_buffer;
 	int opcode, line, status, val;
 	int i;
 	unsigned int rts;
 
+	if (urb->actual_length < 4)
+		return -1;
+
 	/* handle each oob command */
-	for (i = 0; i < urb->actual_length - 3;) {
-		opcode = ((unsigned char *)urb->transfer_buffer)[i++];
-		line = ((unsigned char *)urb->transfer_buffer)[i++];
-		status = ((unsigned char *)urb->transfer_buffer)[i++];
-		val = ((unsigned char *)urb->transfer_buffer)[i++];
+	for (i = 0; i < urb->actual_length - 4; i += 4) {
+		opcode = buf[i];
+		line = buf[i + 1];
+		status = buf[i + 2];
+		val = buf[i + 3];
 
 		dev_dbg(&port->dev, "digi_read_oob_callback: opcode=%d, line=%d, status=%d, val=%d\n",
 			opcode, line, status, val);
-- 
2.11.1