This is a note to let you know that I've just added the patch titled
sctp: update transport state when processing a dupcook packet
to the 4.19-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-update-transport-state-when-processing-a-dupcoo.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 498a5015991392d0078b8862309bfed7cd77c783
Author: Xin Long <lucien.xin@xxxxxxxxx>
Date: Sun Oct 1 10:58:45 2023 -0400
sctp: update transport state when processing a dupcook packet
[ Upstream commit 2222a78075f0c19ca18db53fd6623afb4aff602d ]
During the 4-way handshake, the transport's state is set to ACTIVE in
sctp_process_init() when processing INIT_ACK chunk on client or
COOKIE_ECHO chunk on server.
In the collision scenario below:
192.168.1.2 > 192.168.1.1: sctp (1) [INIT] [init tag: 3922216408]
192.168.1.1 > 192.168.1.2: sctp (1) [INIT] [init tag: 144230885]
192.168.1.2 > 192.168.1.1: sctp (1) [INIT ACK] [init tag: 3922216408]
192.168.1.1 > 192.168.1.2: sctp (1) [COOKIE ECHO]
192.168.1.2 > 192.168.1.1: sctp (1) [COOKIE ACK]
192.168.1.1 > 192.168.1.2: sctp (1) [INIT ACK] [init tag: 3914796021]
when processing COOKIE_ECHO on 192.168.1.2, as it's in COOKIE_WAIT state,
sctp_sf_do_dupcook_b() is called by sctp_sf_do_5_2_4_dupcook() where it
creates a new association and sets its transport to ACTIVE then updates
to the old association in sctp_assoc_update().
However, in sctp_assoc_update(), it will skip the transport update if it
finds a transport with the same ipaddr already existing in the old asoc,
and this causes the old asoc's transport state not to move to ACTIVE
after the handshake.
This means if DATA retransmission happens at this moment, it won't be able
to enter PF state because of the check 'transport->state == SCTP_ACTIVE'
in sctp_do_8_2_transport_strike().
This patch fixes it by updating the transport in sctp_assoc_update() with
sctp_assoc_add_peer() where it updates the transport state if there is
already a transport with the same ipaddr exists in the old asoc.
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Link: https://lore.kernel.org/r/fd17356abe49713ded425250cc1ae51e9f5846c6.1696172325.git.lucien.xin@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index d17708800652a..78c1429d1301c 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -1181,8 +1181,7 @@ int sctp_assoc_update(struct sctp_association *asoc,
/* Add any peer addresses from the new association. */
list_for_each_entry(trans, &new->peer.transport_addr_list,
transports)
- if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr) &&
- !sctp_assoc_add_peer(asoc, &trans->ipaddr,
+ if (!sctp_assoc_add_peer(asoc, &trans->ipaddr,
GFP_ATOMIC, trans->state))
return -ENOMEM;
