firewire: fw-ohci: use of uninitialized data in AR handler

header_length and payload_length are filled with random data if an
unknown tcode was read from the AR buffer (i.e. if the AR buffer
contained invalid data).

We still need a better strategy to recover from this, but at least
handle_ar_packet now doesn't return out of bound buffer addresses
anymore.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/fw-ohci.c

@@ -548,6 +548,11 @@ static __le32 *handle_ar_packet(struct ar_context *ctx, __le32 *buffer)
 		p.header_length = 12;
 		p.payload_length = 0;
 		break;
+
+	default:
+		/* FIXME: Stop context, discard everything, and restart? */
+		p.header_length = 0;
+		p.payload_length = 0;
 	}
 
 	p.payload = (void *) buffer + p.header_length;