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| author | Michal Kubeček <mkubecek@suse.cz> | 2015-03-23 15:14:00 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-04-29 10:31:45 +0200 |
| commit | 344fca2f8283f79e3e3cc647d16da4eaf13da70c (patch) | |
| tree | ef51b8baba3496688e4f35a746034effac0168f9 /net | |
| parent | 5c43c539346972b9a1d5f38dc62db5a39997488d (diff) | |
| download | lwn-344fca2f8283f79e3e3cc647d16da4eaf13da70c.tar.gz lwn-344fca2f8283f79e3e3cc647d16da4eaf13da70c.zip | |
tcp: prevent fetching dst twice in early demux code
[ 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 ACCESS_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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 2 | ||||
| -rw-r--r-- | net/ipv6/tcp_ipv6.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index b7effad5a58c..e2f8bd0d35ed 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1875,7 +1875,7 @@ 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 = ACCESS_ONCE(sk->sk_rx_dst); if (dst) dst = dst_check(dst, 0); diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index a4f890dd223a..9d4332dba8ea 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1633,7 +1633,7 @@ static void tcp_v6_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 = ACCESS_ONCE(sk->sk_rx_dst); if (dst) dst = dst_check(dst, inet6_sk(sk)->rx_dst_cookie); |