From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756777Ab3CYBWL (ORCPT ); Sun, 24 Mar 2013 21:22:11 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:34110 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755381Ab3CYBQd (ORCPT ); Sun, 24 Mar 2013 21:16:33 -0400 Message-Id: <20130325010527.925867168@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 25 Mar 2013 01:06:01 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, Eric Dumazet , Mukesh Agrawal , "David S. Miller" Subject: [ 037/104] tcp: fix skb_availroom() Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In-Reply-To: <20130325010524.240972766@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:f137:78a:b654:affb X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 16fad69cfe4adbbfa813de516757b87bcae36d93 ] Chrome OS team reported a crash on a Pixel ChromeBook in TCP stack : https://code.google.com/p/chromium/issues/detail?id=182056 commit a21d45726acac (tcp: avoid order-1 allocations on wifi and tx path) did a poor choice adding an 'avail_size' field to skb, while what we really needed was a 'reserved_tailroom' one. It would have avoided commit 22b4a4f22da (tcp: fix retransmit of partially acked frames) and this commit. Crash occurs because skb_split() is not aware of the 'avail_size' management (and should not be aware) Signed-off-by: Eric Dumazet Reported-by: Mukesh Agrawal Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- include/linux/skbuff.h | 7 +++++-- net/ipv4/tcp.c | 2 +- net/ipv4/tcp_output.c | 1 - 3 files changed, 6 insertions(+), 4 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 53dc7e7..da65890 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -455,7 +455,7 @@ struct sk_buff { union { __u32 mark; __u32 dropcount; - __u32 avail_size; + __u32 reserved_tailroom; }; __u16 vlan_tci; @@ -1332,7 +1332,10 @@ static inline int skb_tailroom(const struct sk_buff *skb) */ static inline int skb_availroom(const struct sk_buff *skb) { - return skb_is_nonlinear(skb) ? 0 : skb->avail_size - skb->len; + if (skb_is_nonlinear(skb)) + return 0; + + return skb->end - skb->tail - skb->reserved_tailroom; } /** diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 52edbb8..fe381c2 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -704,7 +704,7 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp) * Make sure that we have exactly size bytes * available to the caller, no more, no less. */ - skb->avail_size = size; + skb->reserved_tailroom = skb->end - skb->tail - size; return skb; } __kfree_skb(skb); diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 921cbac..9bb7400 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1096,7 +1096,6 @@ static void __pskb_trim_head(struct sk_buff *skb, int len) eat = min_t(int, len, skb_headlen(skb)); if (eat) { __skb_pull(skb, eat); - skb->avail_size -= eat; len -= eat; if (!len) return;