[PATCH 4.4 124/188] can: gw: synchronize rcu operations before removing gw job entry

Greg Kroah-Hartman
2021-07-19T15:02:45Z

From: Oliver Hartkopp <socketcan@hartkopp.net>

commit fb8696ab14adadb2e3f6c17c18ed26b3ecd96691 upstream.

can_can_gw_rcv() is called under RCU protection, so after calling
can_rx_unregister(), we have to call synchronize_rcu in order to wait
for any RCU read-side critical sections to finish before removing the
kmem_cache entry with the referenced gw job entry.

Link: https://lore.kernel.org/r/20210618173645.2238-1-socketcan@hartkopp.net
Fixes: c1aabdf379bc ("can-gw: add netlink based CAN routing")
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/can/gw.c | 3 +++
1 file changed, 3 insertions(+)

--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -497,6 +497,7 @@ static int cgw_notifier(struct notifier_
if (gwj->src.dev == dev || gwj->dst.dev == dev) {
hlist_del(&gwj->list);
cgw_unregister_filter(gwj);
+ synchronize_rcu();
kmem_cache_free(cgw_cache, gwj);
}
}
@@ -941,6 +942,7 @@ static void cgw_remove_all_jobs(void)
hlist_for_each_entry_safe(gwj, nx, &cgw_list, list) {
hlist_del(&gwj->list);
cgw_unregister_filter(gwj);
+ synchronize_rcu();
kmem_cache_free(cgw_cache, gwj);
}
}
@@ -1008,6 +1010,7 @@ static int cgw_remove_job(struct sk_buff

hlist_del(&gwj->list);
cgw_unregister_filter(gwj);
+ synchronize_rcu();
kmem_cache_free(cgw_cache, gwj);
err = 0;
break;