[PATCH mptcp-net v5 04/20] mptcp: pm: ADD_ADDR rtx: always decrease sk refcount

["Matthieu Baerts (NGI0)" <matttbe@kernel.org>]

When an ADD_ADDR is retransmitted, the sk is held in sk_reset_timer().
It should then be released in all cases at the end.

Some (unlikely) checks were returning directly instead of calling
sock_put() to decrease the refcount. Jump to the 'out' label to fix this
potential leak.

While at it, drop the '!msk' check which cannot happen because it is
never reset, and explicitly mark the remaining one as "unlikely".

Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout")
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
v3: remove '!msk' check: cannot be true.
---
 net/mptcp/pm.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 6a75470dcf5e..d3fcf441b208 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -331,11 +331,8 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 
 	pr_debug("msk=%p\n", msk);
 
-	if (!msk)
-		return;
-
-	if (inet_sk_state_load(sk) == TCP_CLOSE)
-		return;
+	if (unlikely(inet_sk_state_load(sk) == TCP_CLOSE))
+		goto exit;
 
 	bh_lock_sock(sk);
 	if (sock_owned_by_user(sk)) {
@@ -373,6 +370,7 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 
 out:
 	bh_unlock_sock(sk);
+exit:
 	__sock_put(sk);
 }
 

-- 
2.53.0