[PATCH mptcp-net] mptcp: fix extra_subflows leak on failed passive join

[Chenguang Zhao <chenguang.zhao@linux.dev>]

From: Chenguang Zhao <zhaochenguang@kylinos.cn>

mptcp_pm_allow_new_subflow() increments extra_subflows
before __mptcp_finish_join() on the passive MP_JOIN path.
On synchronous join failure the subflow is dropped without
calling mptcp_close_ssk(), so the counter is not rolled back.

Call mptcp_pm_close_subflow() when the join completion fails.

Signed-off-by: Chenguang Zhao <zhaochenguang@kylinos.cn>
---
 net/mptcp/protocol.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index cb9515f505aa..b32f0cd262a7 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3907,6 +3907,7 @@ bool mptcp_finish_join(struct sock *ssk)
 	mptcp_data_unlock(parent);
 
 	if (!ret) {
+		mptcp_pm_close_subflow(msk);
 err_prohibited:
 		subflow->reset_reason = MPTCP_RST_EPROHIBIT;
 		return false;
-- 
2.25.1