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| author | Michal Kubeček <mkubecek@suse.cz> | 2015-03-23 15:14:00 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-03-24 03:38:24 +0100 |
| commit | d0c294c53a771ae7e84506dfbd8c18c30f078735 (patch) | |
| tree | b62e37cf9a4ae8d7bce4410f5a21983ed2025b6d /net/ipv4/tcp_ipv4.c | |
| parent | bnx2x: Fix statistics locking scheme (diff) | |
| download | linux-d0c294c53a771ae7e84506dfbd8c18c30f078735.tar.xz linux-d0c294c53a771ae7e84506dfbd8c18c30f078735.zip | |
tcp: prevent fetching dst twice in early demux code
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@suse.cz>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_ipv4.c')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 5a2dfed4783b..f1756ee02207 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1518,7 +1518,7 @@ void tcp_v4_early_demux(struct sk_buff *skb) 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); |