[patch 05/88] netfilter: nf_conntrack_tcp: fix unaligned memory access in tcp_sack

[Greg KH]

2.6.28-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Mark H. Weaver <mhw@xxxxxxxxxx>

[ Upstream commit 534f81a5068799799e264fd162e9488a129f98d4 ]

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@xxxxxxxxxxxxx>
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 net/netfilter/nf_conntrack_proto_tcp.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -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_buf
 				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;


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