USB: serial: ti_usb_3410_5052: fix array underflow in completion handler

Similarly to a recently reported bug in io_ti, a malicious USB device
could set port_number to a negative value and we would underflow the
port array in the interrupt completion handler.

As these devices only have one or two ports, fix this by making sure we
only consider the seventh bit when determining the port number (and
ignore bits 0xb0 which are typically set to 0x30).

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <[email protected]>
Signed-off-by: Johan Hovold <[email protected]>

diff --git a/drivers/usb/serial/ti_usb_3410_5052.c b/drivers/usb/serial/ti_usb_3410_5052.c
index 3010878f7f8ed9004bb78a15f63e1eb83261742e..e3c5832337e0bdbb83df78285a697ac5f5a8af3f 100644 (file)
--- a/drivers/usb/serial/ti_usb_3410_5052.c
+++ b/drivers/usb/serial/ti_usb_3410_5052.c
@@ -1119,7 +1119,7 @@ static void ti_break(struct tty_struct *tty, int break_state)
 
 static int ti_get_port_from_code(unsigned char code)
 {
-       return (code >> 4) - 3;
+       return (code >> 6) & 0x01;
 }
 
 static int ti_get_func_from_code(unsigned char code)