[PATCH 5.10 051/593] can: gw: synchronize rcu operations before removing gw job entry

From: Greg Kroah-Hartman
Date: Mon Jul 12 2021 - 02:42:39 EST


From: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>

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@xxxxxxxxxxxx
Fixes: c1aabdf379bc ("can-gw: add netlink based CAN routing")
Cc: linux-stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -534,6 +534,7 @@ static int cgw_notifier(struct notifier_
if (gwj->src.dev == dev || gwj->dst.dev == dev) {
hlist_del(&gwj->list);
cgw_unregister_filter(net, gwj);
+ synchronize_rcu();
kmem_cache_free(cgw_cache, gwj);
}
}
@@ -1092,6 +1093,7 @@ static void cgw_remove_all_jobs(struct n
hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) {
hlist_del(&gwj->list);
cgw_unregister_filter(net, gwj);
+ synchronize_rcu();
kmem_cache_free(cgw_cache, gwj);
}
}
@@ -1160,6 +1162,7 @@ static int cgw_remove_job(struct sk_buff

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