mptcp: pm: use _rcu variant under rcu_read_lock

In mptcp_pm_create_subflow_or_signal_addr(), rcu_read_(un)lock() are
used as expected to iterate over the list of local addresses, but
list_for_each_entry() was used instead of list_for_each_entry_rcu() in
__lookup_addr(). It is important to use this variant which adds the
required READ_ONCE() (and diagnostic checks if enabled).

Because __lookup_addr() is also used in mptcp_pm_nl_set_flags() where it
is called under the pernet->lock and not rcu_read_lock(), an extra
condition is then passed to help the diagnostic checks making sure
either the associated spin lock or the RCU lock is held.

Fixes: 86e39e04482b ("mptcp: keep track of local endpoint still available for each msk")
Cc: stable@vger.kernel.org
Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20241112-net-mptcp-misc-6-12-pm-v1-3-b835580cefa8@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index db586a5b3866f66a24431d7f2cab566f89102885..45a2b5f05d38b0e7f334578f5ee6923a8ff8f7b2 100644 (file)
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -524,7 +524,8 @@ __lookup_addr(struct pm_nl_pernet *pernet, const struct mptcp_addr_info *info)
 {
        struct mptcp_pm_addr_entry *entry;
 
-       list_for_each_entry(entry, &pernet->local_addr_list, list) {
+       list_for_each_entry_rcu(entry, &pernet->local_addr_list, list,
+                               lockdep_is_held(&pernet->lock)) {
                if (mptcp_addresses_equal(&entry->addr, info, entry->addr.port))
                        return entry;
        }