[PATCH 3.17 013/319] net: tso: fix unaligned access to crafted TCP header in helper API

[Greg Kroah-Hartman]

3.17-stable review patch.  If anyone has any objections, please let me know.

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

From: Karl Beldan <karl.beldan@xxxxxxxxxxxxxxxx>

[ Upstream commit a63ba13eec092b70d4e5522d692eaeb2f9747387 ]

The crafted header start address is from a driver supplied buffer, which
one can reasonably expect to be aligned on a 4-bytes boundary.
However ATM the TSO helper API is only used by ethernet drivers and
the tcp header will then be aligned to a 2-bytes only boundary from the
header start address.

Signed-off-by: Karl Beldan <karl.beldan@xxxxxxxxxxxxxxxx>
Cc: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/core/tso.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/core/tso.c
+++ b/net/core/tso.c
@@ -1,6 +1,7 @@
 #include <linux/export.h>
 #include <net/ip.h>
 #include <net/tso.h>
+#include <asm/unaligned.h>
 
 /* Calculate expected number of TX descriptors */
 int tso_count_descs(struct sk_buff *skb)
@@ -23,7 +24,7 @@ void tso_build_hdr(struct sk_buff *skb,
 	iph->id = htons(tso->ip_id);
 	iph->tot_len = htons(size + hdr_len - mac_hdr_len);
 	tcph = (struct tcphdr *)(hdr + skb_transport_offset(skb));
-	tcph->seq = htonl(tso->tcp_seq);
+	put_unaligned_be32(tso->tcp_seq, &tcph->seq);
 	tso->ip_id++;
 
 	if (!is_last) {


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