4.9-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 6c7e983b220f89e03286dc70a41c7ef3a8b409df ]
In 9dbbfb0ab6680c6a85609041011484e6658e7d3c function tipc_sk_reinit had additional logic added to loop in the event that function rhashtable_walk_next() returned -EAGAIN. No worries.
However, if rhashtable_walk_start returns -EAGAIN, it does "continue", and therefore skips the call to rhashtable_walk_stop(). That has the effect of calling rcu_read_lock() without its paired call to rcu_read_unlock(). Since rcu_read_lock() may be nested, the problem may not be apparent for a while, especially since resize events may be rare. But the comments to rhashtable_walk_start() state:
* ...Note that we take the RCU lock in all * cases including when we return an error. So you must always call * rhashtable_walk_stop to clean up.
This patch replaces the continue with a goto and label to ensure a matching call to rhashtable_walk_stop().
Signed-off-by: Bob Peterson rpeterso@redhat.com Acked-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/tipc/socket.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/tipc/socket.c b/net/tipc/socket.c index 25bc5c30d7fb..9d3f047305ce 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -2277,8 +2277,8 @@ void tipc_sk_reinit(struct net *net)
do { tsk = ERR_PTR(rhashtable_walk_start(&iter)); - if (tsk) - continue; + if (IS_ERR(tsk)) + goto walk_stop;
while ((tsk = rhashtable_walk_next(&iter)) && !IS_ERR(tsk)) { spin_lock_bh(&tsk->sk.sk_lock.slock); @@ -2287,7 +2287,7 @@ void tipc_sk_reinit(struct net *net) msg_set_orignode(msg, tn->own_addr); spin_unlock_bh(&tsk->sk.sk_lock.slock); } - +walk_stop: rhashtable_walk_stop(&iter); } while (tsk == ERR_PTR(-EAGAIN)); }