Commit d7ab5cdc authored by Xin Long's avatar Xin Long Committed by David S. Miller

sctp: update dst pmtu with the correct daddr

When processing pmtu update from an icmp packet, it calls .update_pmtu
with sk instead of skb in sctp_transport_update_pmtu.

However for sctp, the daddr in the transport might be different from
inet_sock->inet_daddr or sk->sk_v6_daddr, which is used to update or
create the route cache. The incorrect daddr will cause a different
route cache created for the path.

So before calling .update_pmtu, inet_sock->inet_daddr/sk->sk_v6_daddr
should be updated with the daddr in the transport, and update it back
after it's done.

The issue has existed since route exceptions introduction.

Fixes: 4895c771 ("ipv4: Add FIB nexthop exceptions.")
Signed-off-by: default avatarXin Long <>
Acked-by: default avatarMarcelo Ricardo Leitner <>
Signed-off-by: default avatarDavid S. Miller <>
parent 8c6ec361
......@@ -260,6 +260,7 @@ void sctp_transport_pmtu(struct sctp_transport *transport, struct sock *sk)
bool sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu)
struct dst_entry *dst = sctp_transport_dst_check(t);
struct sock *sk = t->asoc->;
bool change = true;
if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) {
......@@ -271,12 +272,19 @@ bool sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu)
pmtu = SCTP_TRUNC4(pmtu);
if (dst) {
dst->ops->update_pmtu(dst, t->asoc->, NULL, pmtu);
struct sctp_pf *pf = sctp_get_pf_specific(dst->ops->family);
union sctp_addr addr;
pf->af->from_sk(&addr, sk);
pf->to_sk_daddr(&t->ipaddr, sk);
dst->ops->update_pmtu(dst, sk, NULL, pmtu);
pf->to_sk_daddr(&addr, sk);
dst = sctp_transport_dst_check(t);
if (!dst) {
t->af_specific->get_dst(t, &t->saddr, &t->fl, t->asoc->;
t->af_specific->get_dst(t, &t->saddr, &t->fl, sk);
dst = t->dst;
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