netdev - [PATCH net-next] sctp: reset ret in again path in sctp_for_each

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Date:   Tue, 23 Jan 2018 18:22:25 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org
Cc:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Neil Horman <nhorman@...driver.com>, davem@...emloft.net
Subject: [PATCH net-next] sctp: reset ret in again path in sctp_for_each_transport

Commit 97a6ec4ac021 ("rhashtable: Change rhashtable_walk_start to
return void") only initialized ret for the first time, when going
to again path, the next tsp could be NULL. Without resetting ret,
cb_done would be called with tsp as NULL.

A kernel crash was caused by this when running sctpdiag testcase
in sctp-tests.

Note that this issue doesn't affect net.git yet.

Fixes: 97a6ec4ac021 ("rhashtable: Change rhashtable_walk_start to return void")
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/sctp/socket.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 7ff444e..a40fa53 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4860,9 +4860,10 @@ int sctp_for_each_transport(int (*cb)(struct sctp_transport *, void *),
 			    struct net *net, int *pos, void *p) {
 	struct rhashtable_iter hti;
 	struct sctp_transport *tsp;
-	int ret = 0;
+	int ret;
 
 again:
+	ret = 0;
 	sctp_transport_walk_start(&hti);
 
 	tsp = sctp_transport_get_idx(net, &hti, *pos + 1);
-- 
2.1.0