[PATCH] USB: serial: digi_acceleport: fix OOB-event processing

[Johan Hovold <johan@kernel.org>]

A recent change claimed to fix an off-by-one error in the OOB-port
completion handler, but instead introduced such an error. This could
specifically led to modem-status changes going unnoticed, effectively
breaking TIOCMGET.

Note that the offending commit fixes a loop-condition underflow and is
marked for stable, but should not be backported without this fix.

Reported-by: Ben Hutchings <ben@decadent.org.uk>
Fixes: 2d380889215f ("USB: serial: digi_acceleport: fix OOB data sanity
check")
Cc: stable <stable@vger.kernel.org>	# v2.6.30
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/digi_acceleport.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/serial/digi_acceleport.c b/drivers/usb/serial/digi_acceleport.c
index eb433922598c..7ab3235febfc 100644
--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -1499,7 +1499,7 @@ static int digi_read_oob_callback(struct urb *urb)
 		return -1;
 
 	/* handle each oob command */
-	for (i = 0; i < urb->actual_length - 4; i += 4) {
+	for (i = 0; i < urb->actual_length - 3; i += 4) {
 		opcode = buf[i];
 		line = buf[i + 1];
 		status = buf[i + 2];
-- 
2.11.1