[NETFILTER] arp_tables: Fix unaligned accesses.

There are two device string comparison loops in arp_packet_match().
The first one goes byte-by-byte but the second one tries to be
clever and cast the string to a long and compare by longs.

The device name strings in the arp table entries are not guarenteed
to be aligned enough to make this value, so just use byte-by-byte
for both cases.

Based upon a report by <[e-mail]>.

Signed-off-by: David S. Miller <[e-mail]>

net/ipv4/netfilter/arp_tables.c

···
 		return 0;
 	}
 
-	for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned long); i++) {
-		unsigned long odev;
-		memcpy(&odev, outdev + i*sizeof(unsigned long),
-		       sizeof(unsigned long));
-		ret |= (odev
-			^ ((const unsigned long *)arpinfo->outiface)[i])
-			& ((const unsigned long *)arpinfo->outiface_mask)[i];
+	for (i = 0, ret = 0; i < IFNAMSIZ; i++) {
+		ret |= (outdev[i] ^ arpinfo->outiface[i])
+			& arpinfo->outiface_mask[i];
 	}
 
 	if (FWINV(ret != 0, ARPT_INV_VIA_OUT)) {