From: Eric Dumazet edumazet@google.com
[ Upstream commit a20ea298071f46effa3aaf965bf9bb34c901db3f ]
sctp_rcv() reads sk->sk_bound_dev_if twice while the socket is not locked. Another cpu could change this field under us.
Fixes: 0fd9a65a76e8 ("[SCTP] Support SO_BINDTODEVICE socket option on incoming packets.") Signed-off-by: Eric Dumazet edumazet@google.com Cc: Neil Horman nhorman@tuxdriver.com Cc: Vlad Yasevich vyasevich@gmail.com Cc: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Acked-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/sctp/input.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/sctp/input.c b/net/sctp/input.c index 9c1670b4a687..ed3a8a66a00b 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -103,6 +103,7 @@ int sctp_rcv(struct sk_buff *skb) struct sctp_chunk *chunk; union sctp_addr src; union sctp_addr dest; + int bound_dev_if; int family; struct sctp_af *af; struct net *net = dev_net(skb->dev); @@ -180,7 +181,8 @@ int sctp_rcv(struct sk_buff *skb) * If a frame arrives on an interface and the receiving socket is * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB */ - if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) { + bound_dev_if = READ_ONCE(sk->sk_bound_dev_if); + if (bound_dev_if && (bound_dev_if != af->skb_iif(skb))) { if (transport) { sctp_transport_put(transport); asoc = NULL;