| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 095/126] packet: fix match_fanout_group() | Date | Wed, 9 Dec 2015 09:37:45 +0000 |
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3.16.7-ckt21 -stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
commit 161642e24fee40fba2c5bc2ceacc00d118a22d65 upstream.
Recent TCP listener patches exposed a prior af_packet bug : match_fanout_group() blindly assumes it is always safe to cast sk to a packet socket to compare fanout with af_packet_priv
But SYNACK packets can be sent while attached to request_sock, which are smaller than a "struct sock".
We can read non existent memory and crash.
Fixes: c0de08d04215 ("af_packet: don't emit packet on orig fanout group") Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Cc: Eric Leblond <eric@regit.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- net/packet/af_packet.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index e6bd6df9e2a2..1f618bbce0ac 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1412,10 +1412,10 @@ static void __fanout_unlink(struct sock *sk, struct packet_sock *po) static bool match_fanout_group(struct packet_type *ptype, struct sock *sk) { - if (ptype->af_packet_priv == (void *)((struct packet_sock *)sk)->fanout) - return true; + if (sk->sk_family != PF_PACKET) + return false; - return false; + return ptype->af_packet_priv == pkt_sk(sk)->fanout; } static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
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