From: Xin Long lucien.xin@gmail.com
[ 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 --- include/net/sctp/sctp.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h index bc00410223b03..189fdb9db1622 100644 --- a/include/net/sctp/sctp.h +++ b/include/net/sctp/sctp.h @@ -626,7 +626,8 @@ static inline __u32 sctp_min_frag_point(struct sctp_sock *sp, __u16 datasize)
static inline int sctp_transport_pl_hlen(struct sctp_transport *t) { - return __sctp_mtu_payload(sctp_sk(t->asoc->base.sk), t, 0, 0); + return __sctp_mtu_payload(sctp_sk(t->asoc->base.sk), t, 0, 0) - + sizeof(struct sctphdr); }
static inline void sctp_transport_pl_reset(struct sctp_transport *t)