This is a note to let you know that I've just added the patch titled
sctp: subtract sctphdr len in sctp_transport_pl_hlen
to the 5.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sctp-subtract-sctphdr-len-in-sctp_transport_pl_hlen.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1f7cbb831bcaec7b5d2fbfb459277fdcb4eafb6e
Author: Xin Long <lucien.xin@xxxxxxxxx>
Date: Thu Oct 28 05:36:03 2021 -0400
sctp: subtract sctphdr len in sctp_transport_pl_hlen
[ 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@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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)
