From 21df56c6e2372e09c916111efb6c14c372a5ab2e Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Sun, 18 Nov 2007 18:48:08 -0800
Subject: [PATCH] [TCP]: Fix TCP header misalignment
Indeed my previous change to alloc_pskb has made it possible
for the TCP header to be misaligned iff the MTU is not a multiple
of 4 (and less than a page). So I suspect the optimised IPsec
MTU calculation is giving you just such an MTU :)
This patch fixes it by changing alloc_pskb to make sure that
the size is at least 32-bit aligned. This does not cause the
problem fixed by the previous patch because max_header is always
32-bit aligned which means that in the SG/NOTSO case this will
be a no-op.
I thought about putting this in the callers but all the current
callers are from TCP. If and when we get a non-TCP caller we
can always create a TCP wrapper for this function and move the
alignment over there.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/net/sock.h | 3 +++
1 file changed, 3 insertions(+)
diff --git a/include/net/sock.h b/include/net/sock.h
index 567e468d7492..67e35c7e230c 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1236,6 +1236,9 @@ static inline struct sk_buff *sk_stream_alloc_pskb(struct sock *sk,
{
struct sk_buff *skb;
+ /* The TCP header must be at least 32-bit aligned. */
+ size = ALIGN(size, 4);
+
skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
if (skb) {
skb->truesize += mem;
--
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