554153b1cd
[ Upstream commit cc4665ca646c96181a7c00198aa72c59e0c576e8 ]
sctp_transport_pl_hlen() is called to calculate the outer header length
for PL. However, as the Figure in rfc8899#section-4.4:
Any additional
headers .--- MPS -----.
| | |
v v v
+------------------------------+
| IP | ** | PL | protocol data |
+------------------------------+
<----- PLPMTU ----->
<---------- PMTU -------------->
Outer header are IP + Any additional headers, which doesn't include
Packetization Layer itself header, namely sctphdr, whereas sctphdr
is counted by __sctp_mtu_payload().
The incorrect calculation caused the link pathmtu to be set larger
than expected by t->pl.pmtu + sctp_transport_pl_hlen(). This patch
is to fix it by subtracting sctphdr len in sctp_transport_pl_hlen().
Fixes: d9e2e410ae30 ("sctp: add the constants/variables and states and some APIs for transport")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>