linux-kernel - [34-longterm 111/260] gro: Re-fix different skb headrooms

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Message-Id: <1293952756-15010-112-git-send-email-paul.gortmaker@windriver.com>
Date:	Sun,  2 Jan 2011 02:16:47 -0500
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org, Jarek Poplawski <jarkao2@...il.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 111/260] gro: Re-fix different skb headrooms

From: Jarek Poplawski <jarkao2@...il.com>

commit 64289c8e6851bca0e589e064c9a5c9fbd6ae5dd4 upstream.

The patch: "gro: fix different skb headrooms" in its part:
"2) allocate a minimal skb for head of frag_list" is buggy. The copied
skb has p->data set at the ip header at the moment, and skb_gro_offset
is the length of ip + tcp headers. So, after the change the length of
mac header is skipped. Later skb_set_mac_header() sets it into the
NET_SKB_PAD area (if it's long enough) and ip header is misaligned at
NET_SKB_PAD + NET_IP_ALIGN offset. There is no reason to assume the
original skb was wrongly allocated, so let's copy it as it was.

bugzilla : https://bugzilla.kernel.org/show_bug.cgi?id=16626
fixes commit: 3d3be4333fdf6faa080947b331a6a19bce1a4f57

Reported-by: Plamen Petrov <pvp-lsts@...uni-ruse.bg>
Signed-off-by: Jarek Poplawski <jarkao2@...il.com>
CC: Eric Dumazet <eric.dumazet@...il.com>
Acked-by: Eric Dumazet <eric.dumazet@...il.com>
Tested-by: Plamen Petrov <pvp-lsts@...uni-ruse.bg>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 net/core/skbuff.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index c1c86f5..9e7214e 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2711,7 +2711,7 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
 	} else if (skb_gro_len(p) != pinfo->gso_size)
 		return -E2BIG;
 
-	headroom = NET_SKB_PAD + NET_IP_ALIGN;
+	headroom = skb_headroom(p);
 	nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC);
 	if (unlikely(!nskb))
 		return -ENOMEM;
-- 
1.7.3.3

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