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

[Karl Beldan]

From: Karl Beldan <***@rivierawaves.com>

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 <***@rivierawaves.com>
Cc: Ezequiel Garcia <***@free-electrons.com>
---
net/core/tso.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/tso.c b/net/core/tso.c
index 8c3203c..630b30b 100644
--- 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, char *hdr, struct tso_t *tso,
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) {

[David Miller]

From: Karl Beldan <***@gmail.com>
Date: Tue, 21 Oct 2014 16:06:05 +0200

Post by Karl Beldan
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.

Applied, thank you.