netfilter: nf_conntrack_tcp: fix unaligned memory access in tcp_sack

This patch fixes an unaligned memory access in tcp_sack while reading
sequence numbers from TCP selective acknowledgement options.  Prior to
applying this patch, upstream linux-2.6.27.20 was occasionally
generating messages like this on my sparc64 system:

  [54678.532071] Kernel unaligned access at TPC[6b17d4] tcp_packet+0xcd4/0xd00

Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Mark H. Weaver 2009-03-23 13:46:12 +01:00 committed by Patrick McHardy
parent d1238d5337
commit 534f81a506

View File

@ -15,6 +15,7 @@
#include <linux/skbuff.h>
#include <linux/ipv6.h>
#include <net/ip6_checksum.h>
#include <asm/unaligned.h>
#include <net/tcp.h>
@ -466,7 +467,7 @@ static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
for (i = 0;
i < (opsize - TCPOLEN_SACK_BASE);
i += TCPOLEN_SACK_PERBLOCK) {
tmp = ntohl(*((__be32 *)(ptr+i)+1));
tmp = get_unaligned_be32((__be32 *)(ptr+i)+1);
if (after(tmp, *sack))
*sack = tmp;