netdev - [PATCH v2] net: sctp: Fix negotiation of the number of data streams.

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Message-ID: <1f2ffcb1180e4080aab114683b06efab@AcuMS.aculab.com>
Date:   Wed, 19 Aug 2020 14:40:52 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     David Laight <David.Laight@...LAB.COM>,
        "'netdev@...r.kernel.org'" <netdev@...r.kernel.org>,
        "'linux-sctp@...r.kernel.org'" <linux-sctp@...r.kernel.org>
CC:     'Marcelo Ricardo Leitner' <marcelo.leitner@...il.com>
Subject: [PATCH v2] net: sctp: Fix negotiation of the number of data streams.


The number of output and input streams was never being reduced, eg when
processing received INIT or INIT_ACK chunks.
The effect is that DATA chunks can be sent with invalid stream ids
and then discarded by the remote system.

Fixes: 2075e50caf5ea ("sctp: convert to genradix")
Signed-off-by: David Laight <david.laight@...lab.com>
---
 net/sctp/stream.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

This needs backporting to 5.1 and all later kernels.

(Resend without the RE:)

Changes since v1:
- Fix 'Fixes' tag.
- Improve description.

diff --git a/net/sctp/stream.c b/net/sctp/stream.c
index bda2536dd740..6dc95dcc0ff4 100644
--- a/net/sctp/stream.c
+++ b/net/sctp/stream.c
@@ -88,12 +88,13 @@ static int sctp_stream_alloc_out(struct sctp_stream *stream, __u16 outcnt,
 	int ret;
 
 	if (outcnt <= stream->outcnt)
-		return 0;
+		goto out;
 
 	ret = genradix_prealloc(&stream->out, outcnt, gfp);
 	if (ret)
 		return ret;
 
+out:
 	stream->outcnt = outcnt;
 	return 0;
 }
@@ -104,12 +105,13 @@ static int sctp_stream_alloc_in(struct sctp_stream *stream, __u16 incnt,
 	int ret;
 
 	if (incnt <= stream->incnt)
-		return 0;
+		goto out;
 
 	ret = genradix_prealloc(&stream->in, incnt, gfp);
 	if (ret)
 		return ret;
 
+out:
 	stream->incnt = incnt;
 	return 0;
 }
-- 
2.25.1

-
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