| From stable-bounces@linux.kernel.org Thu Nov 29 04:09:05 2007 |
| From: Herbert Xu <herbert@gondor.apana.org.au> |
| Date: Thu, 29 Nov 2007 23:07:58 +1100 |
| Subject: TCP: Fix TCP header misalignment |
| To: stable@kernel.org, davem@davemloft.net |
| Message-ID: <E1IxiBS-0007sy-00@gondolin.me.apana.org.au> |
| |
| From: Herbert Xu <herbert@gondor.apana.org.au> |
| |
| [TCP]: Fix TCP header misalignment |
| |
| [ Upstream commit: 21df56c6e2372e09c916111efb6c14c372a5ab2e ] |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| include/net/sock.h | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| --- a/include/net/sock.h |
| +++ b/include/net/sock.h |
| @@ -1200,6 +1200,9 @@ static inline struct sk_buff *sk_stream_ |
| { |
| 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; |
