From: Eric Dumazet <[email protected]>
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 <[email protected]>
Cc: Willem de Bruijn <[email protected]>
Cc: Eric Leblond <[email protected]>
---
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 81c900fbc4a4..ccd1d4e9b151 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1519,10 +1519,10 @@ 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 void fanout_init_data(struct packet_fanout *f)
--
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