USB: serial: safe_serial: fix information leak in completion handler

Add missing sanity check to the bulk-in completion handler to avoid an integer underflow that could be triggered by a malicious device. This avoids leaking up to 56 bytes from after the URB transfer buffer to user space. Fixes: 1da177e ("Linux-2.6.12-rc2") Cc: stable <[email protected]> Signed-off-by: Johan Hovold <[email protected]>
redbrain17 · Mar 8, 2017 · 8c76d7c · 8c76d7c
1 parent 654b404
commit 8c76d7c
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/drivers/usb/serial/safe_serial.c b/drivers/usb/serial/safe_serial.c
@@ -200,6 +200,11 @@ static void safe_process_read_urb(struct urb *urb)
 	if (!safe)
 		goto out;
 
+	if (length < 2) {
+		dev_err(&port->dev, "malformed packet\n");
+		return;
+	}
+
 	fcs = fcs_compute10(data, length, CRC10_INITFCS);
 	if (fcs) {
 		dev_err(&port->dev, "%s - bad CRC %x\n", __func__, fcs);