[PATCH] mptcp: hold pm lock when deleting entry

[Geliang Tang <geliang@xxxxxxxxxx>]

When traversing userspace_pm_local_addr_list and deleting an entry from
it in mptcp_pm_nl_remove_doit(), msk->pm.lock should be held.

This patch holds this lock before mptcp_userspace_pm_lookup_addr_by_id()
and releases it after list_move() in mptcp_pm_nl_remove_doit().

Fixes: d9a4594edabf ("mptcp: netlink: Add MPTCP_PM_CMD_REMOVE")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Geliang Tang <tanggeliang@xxxxxxxxxx>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Link: https://patch.msgid.link/20241112-net-mptcp-misc-6-12-pm-v1-2-b835580cefa8@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>

diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c
index 3f888bfe1462..e35178f5205f 100644
--- a/net/mptcp/pm_userspace.c
+++ b/net/mptcp/pm_userspace.c
@@ -308,14 +308,17 @@ int mptcp_pm_nl_remove_doit(struct sk_buff *skb, struct genl_info *info)
 
 	lock_sock(sk);
 
+	spin_lock_bh(&msk->pm.lock);
 	match = mptcp_userspace_pm_lookup_addr_by_id(msk, id_val);
 	if (!match) {
 		GENL_SET_ERR_MSG(info, "address with specified id not found");
+		spin_unlock_bh(&msk->pm.lock);
 		release_sock(sk);
 		goto out;
 	}
 
 	list_move(&match->list, &free_list);
+	spin_unlock_bh(&msk->pm.lock);
 
 	mptcp_pm_remove_addrs(msk, &free_list);