4.18-stable review patch. If anyone has any objections, please let me know.
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From: Xin Long lucien.xin@gmail.com
[ Upstream commit d7ab5cdce54da631f0c8c11e506c974536a3581e ]
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: 4895c771c7f0 ("ipv4: Add FIB nexthop exceptions.") Reported-by: ian.periam@dialogic.com Signed-off-by: Xin Long lucien.xin@gmail.com Acked-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sctp/transport.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
--- a/net/sctp/transport.c +++ b/net/sctp/transport.c @@ -260,6 +260,7 @@ void sctp_transport_pmtu(struct sctp_tra 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->base.sk; bool change = true;
if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) { @@ -271,12 +272,19 @@ bool sctp_transport_update_pmtu(struct s pmtu = SCTP_TRUNC4(pmtu);
if (dst) { - dst->ops->update_pmtu(dst, t->asoc->base.sk, 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->base.sk); + t->af_specific->get_dst(t, &t->saddr, &t->fl, sk); dst = t->dst; }