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

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

[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-next 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 also be merged in the next major kernel release
during the merge window.

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