Patch "sctp: return next obj by passing pos + 1 into sctp_transport_get_idx" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    sctp: return next obj by passing pos + 1 into sctp_transport_get_idx

to the 4.9-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-return-next-obj-by-passing-pos-1-into-sctp_transport_get_idx.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Jun 29 18:57:46 CEST 2017
From: Xin Long <lucien.xin@gmail.com>
Date: Thu, 15 Jun 2017 17:49:08 +0800
Subject: sctp: return next obj by passing pos + 1 into sctp_transport_get_idx

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


[ Upstream commit 988c7322116970696211e902b468aefec95b6ec4 ]

In sctp_for_each_transport, pos is used to save how many objs it has
dumped. Now it gets the last obj by sctp_transport_get_idx, then gets
the next obj by sctp_transport_get_next.

The issue is that in the meanwhile if some objs in transport hashtable
are removed and the objs nums are less than pos, sctp_transport_get_idx
would return NULL and hti.walker.tbl is NULL as well. At this moment
it should stop hti, instead of continue getting the next obj. Or it
would cause a NULL pointer dereference in sctp_transport_get_next.

This patch is to pass pos + 1 into sctp_transport_get_idx to get the
next obj directly, even if pos > objs nums, it would return NULL and
stop hti.

Fixes: 626d16f50f39 ("sctp: export some apis or variables for sctp_diag and reuse some for proc")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sctp/socket.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4506,9 +4506,8 @@ int sctp_for_each_transport(int (*cb)(st
 	if (err)
 		return err;
 
-	sctp_transport_get_idx(net, &hti, pos);
-	obj = sctp_transport_get_next(net, &hti);
-	for (; obj && !IS_ERR(obj); obj = sctp_transport_get_next(net, &hti)) {
+	obj = sctp_transport_get_idx(net, &hti, pos + 1);
+	for (; !IS_ERR_OR_NULL(obj); obj = sctp_transport_get_next(net, &hti)) {
 		struct sctp_transport *transport = obj;
 
 		if (!sctp_transport_hold(transport))


Patches currently in stable-queue which might be from lucien.xin@gmail.com are

queue-4.9/ipv6-fix-calling-in6_ifa_hold-incorrectly-for-dad-work.patch
queue-4.9/igmp-acquire-pmc-lock-for-ip_mc_clear_src.patch
queue-4.9/sctp-return-next-obj-by-passing-pos-1-into-sctp_transport_get_idx.patch
queue-4.9/sctp-disable-bh-in-sctp_for_each_endpoint.patch