[PATCH] pktcdvd: Fix overflow for discs with large packets

The pktcdvd driver was using an 8 bit field to store the packet length
obtained from the disc track info.  This causes it to overflow packet length
values of 128KB or more.  I changed the field to 32 bits to fix this.

The pktcdvd driver defaulted to its maximum allowed packet length when it
detected a 0 in the track info field.  I changed this to fail the operation
and refuse to access the media.  This seems more sane than attempting to
access it with a value that almost certainly will not work.
Signed-off-by: NPeter Osterlund <petero2@telia.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/block/pktcdvd.c

@@ -1639,7 +1639,7 @@ static int pkt_probe_settings(struct pktcdvd_device *pd)
 	pd->settings.size = be32_to_cpu(ti.fixed_packet_size) << 2;
 	if (pd->settings.size == 0) {
 		printk("pktcdvd: detected zero packet size!\n");
-		pd->settings.size = 128;
+		return -ENXIO;
 	}
 	if (pd->settings.size > PACKET_MAX_SECTORS) {
 		printk("pktcdvd: packet size is too big\n");

include/linux/pktcdvd.h

@@ -114,7 +114,7 @@ struct pkt_ctrl_command {
 
 struct packet_settings
 {
-	__u8			size;		/* packet size in (512 byte) sectors */
+	__u32			size;		/* packet size in (512 byte) sectors */
 	__u8			fp;		/* fixed packets */
 	__u8			link_loss;	/* the rest is specified
 						 * as per Mt Fuji */