linux-kernel - [PATCH 3.16 251/366] sctp: fix the issue that the cookie-ack with auth can't get processed

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Message-ID: <lsq.1539530741.875700982@decadent.org.uk>
Date:   Sun, 14 Oct 2018 16:25:41 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Neil Horman" <nhorman@...driver.com>,
        "Marcelo Ricardo Leitner" <marcelo.leitner@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        "Xin Long" <lucien.xin@...il.com>
Subject: [PATCH 3.16 251/366] sctp: fix the issue that the cookie-ack with
 auth can't get processed

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Xin Long <lucien.xin@...il.com>

commit ce402f044e4e432c296f90eaabb8dbe8f3624391 upstream.

When auth is enabled for cookie-ack chunk, in sctp_inq_pop, sctp
processes auth chunk first, then continues to the next chunk in
this packet if chunk_end + chunk_hdr size < skb_tail_pointer().
Otherwise, it will go to the next packet or discard this chunk.

However, it missed the fact that cookie-ack chunk's size is equal
to chunk_hdr size, which couldn't match that check, and thus this
chunk would not get processed.

This patch fixes it by changing the check to chunk_end + chunk_hdr
size <= skb_tail_pointer().

Fixes: 26b87c788100 ("net: sctp: fix remote memory pressure from excessive queueing")
Signed-off-by: Xin Long <lucien.xin@...il.com>
Acked-by: Neil Horman <nhorman@...driver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/sctp/inqueue.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/sctp/inqueue.c
+++ b/net/sctp/inqueue.c
@@ -178,7 +178,7 @@ struct sctp_chunk *sctp_inq_pop(struct s
 	skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
 	chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 
-	if (chunk->chunk_end + sizeof(sctp_chunkhdr_t) <
+	if (chunk->chunk_end + sizeof(sctp_chunkhdr_t) <=
 	    skb_tail_pointer(chunk->skb)) {
 		/* This is not a singleton */
 		chunk->singleton = 0;