3.2.89-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Johan Hovold <johan@xxxxxxxxxx>
commit 2d380889215fe20b8523345649dee0579821800c upstream.
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")
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
drivers/usb/serial/digi_acceleport.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -1746,6 +1746,7 @@ static int digi_read_oob_callback(struct
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;
@@ -1753,12 +1754,15 @@ static int digi_read_oob_callback(struct
dbg("digi_read_oob_callback: port=%d, len=%d",
priv->dp_port_num, urb->actual_length);
+ 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];
dbg("digi_read_oob_callback: opcode=%d, line=%d, status=%d, val=%d",
opcode, line, status, val);