From: Xin Long Date: Wed, 18 Oct 2017 13:37:49 +0000 (+0800) Subject: sctp: add the missing sock_owned_by_user check in sctp_icmp_redirect X-Git-Tag: archive/raspbian/4.9.80-2+rpi1~7^2~1342 X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/%22/%22http:/www.example.com/cgi/%22?a=commitdiff_plain;h=bcb9ced1833c4cafb425077d8114d9d23de0ef95;p=linux-4.9.git sctp: add the missing sock_owned_by_user check in sctp_icmp_redirect [ Upstream commit 1cc276cec9ec574d41cf47dfc0f51406b6f26ab4 ] Now sctp processes icmp redirect packet in sctp_icmp_redirect where it calls sctp_transport_dst_check in which tp->dst can be released. The problem is before calling sctp_transport_dst_check, it doesn't check sock_owned_by_user, which means tp->dst could be freed while a process is accessing it with owning the socket. An use-after-free issue could be triggered by this. This patch is to fix it by checking sock_owned_by_user before calling sctp_transport_dst_check in sctp_icmp_redirect, so that it would not release tp->dst if users still hold sock lock. Besides, the same issue fixed in commit 45caeaa5ac0b ("dccp/tcp: fix routing redirect race") on sctp also needs this check. Fixes: 55be7a9c6074 ("ipv4: Add redirect support to all protocol icmp error handlers") Reported-by: Eric Dumazet Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Acked-by: Neil Horman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/sctp/input.c b/net/sctp/input.c index 6c79915c7dbc..68b84d3a7cac 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -421,7 +421,7 @@ void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t, { struct dst_entry *dst; - if (!t) + if (sock_owned_by_user(sk) || !t) return; dst = sctp_transport_dst_check(t); if (dst)