This is a note to let you know that I've just added the patch titled
tcp: prevent fetching dst twice in early demux code
to the 3.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tcp-prevent-fetching-dst-twice-in-early-demux-code.patch
and it can be found in the queue-3.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Apr 21 23:05:14 CEST 2015
From: =?UTF-8?q?Michal=20Kube=C4=8Dek?= <mkubecek@xxxxxxx>
Date: Mon, 23 Mar 2015 15:14:00 +0100
Subject: tcp: prevent fetching dst twice in early demux code
From: =?UTF-8?q?Michal=20Kube=C4=8Dek?= <mkubecek@xxxxxxx>
[ Upstream commit d0c294c53a771ae7e84506dfbd8c18c30f078735 ]
On s390x, gcc 4.8 compiles this part of tcp_v6_early_demux()
struct dst_entry *dst = sk->sk_rx_dst;
if (dst)
dst = dst_check(dst, inet6_sk(sk)->rx_dst_cookie);
to code reading sk->sk_rx_dst twice, once for the test and once for
the argument of ip6_dst_check() (dst_check() is inline). This allows
ip6_dst_check() to be called with null first argument, causing a crash.
Protect sk->sk_rx_dst access by READ_ONCE() both in IPv4 and IPv6
TCP early demux code.
Fixes: 41063e9dd119 ("ipv4: Early TCP socket demux.")
Fixes: c7109986db3c ("ipv6: Early TCP socket demux")
Signed-off-by: Michal Kubecek <mkubecek@xxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/tcp_ipv4.c | 2 +-
net/ipv6/tcp_ipv6.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1516,7 +1516,7 @@ void tcp_v4_early_demux(struct sk_buff *
skb->sk = sk;
skb->destructor = sock_edemux;
if (sk->sk_state != TCP_TIME_WAIT) {
- struct dst_entry *dst = sk->sk_rx_dst;
+ struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst);
if (dst)
dst = dst_check(dst, 0);
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1583,7 +1583,7 @@ static void tcp_v6_early_demux(struct sk
skb->sk = sk;
skb->destructor = sock_edemux;
if (sk->sk_state != TCP_TIME_WAIT) {
- struct dst_entry *dst = sk->sk_rx_dst;
+ struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst);
if (dst)
dst = dst_check(dst, inet6_sk(sk)->rx_dst_cookie);
Patches currently in stable-queue which might be from mkubecek@xxxxxxx are
queue-3.19/tcp-prevent-fetching-dst-twice-in-early-demux-code.patch
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