netdev - [PATCH net 2/2] sctp: shrink stream outq when fails to do addstream reconf

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <b4172cd23a6369c12a483e58f14619640aaf24ae.1595433039.git.lucien.xin@gmail.com>
Date:   Wed, 22 Jul 2020 23:52:12 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org
Cc:     davem@...emloft.net,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Neil Horman <nhorman@...driver.com>
Subject: [PATCH net 2/2] sctp: shrink stream outq when fails to do addstream reconf

When adding a stream with stream reconf, the new stream firstly is in
CLOSED state but new out chunks can still be enqueued. Then once gets
the confirmation from the peer, the state will change to OPEN.

However, if the peer denies, it needs to roll back the stream. But when
doing that, it only sets the stream outcnt back, and the chunks already
in the new stream don't get purged. It caused these chunks can still be
dequeued in sctp_outq_dequeue_data().

As its stream is still in CLOSE, the chunk will be enqueued to the head
again by sctp_outq_head_data(). This chunk will never be sent out, and
the chunks after it can never be dequeued. The assoc will be 'hung' in
a dead loop of sending this chunk.

To fix it, this patch is to purge these chunks already in the new
stream by calling sctp_stream_shrink_out() when failing to do the
addstream reconf.

Fixes: 11ae76e67a17 ("sctp: implement receiver-side procedures for the Reconf Response Parameter")
Reported-by: Ying Xu <yinxu@...hat.com>
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/sctp/stream.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/sctp/stream.c b/net/sctp/stream.c
index 4f87693..bda2536 100644
--- a/net/sctp/stream.c
+++ b/net/sctp/stream.c
@@ -1044,11 +1044,13 @@ struct sctp_chunk *sctp_process_strreset_resp(
 		nums = ntohs(addstrm->number_of_streams);
 		number = stream->outcnt - nums;

-		if (result == SCTP_STRRESET_PERFORMED)
+		if (result == SCTP_STRRESET_PERFORMED) {
 			for (i = number; i < stream->outcnt; i++)
 				SCTP_SO(stream, i)->state = SCTP_STREAM_OPEN;
-		else
+		} else {
+			sctp_stream_shrink_out(stream, number);
 			stream->outcnt = number;
+		}

 		*evp = sctp_ulpevent_make_stream_change_event(asoc, flags,
 			0, nums, GFP_ATOMIC);
-- 
2.1.0