The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From fb8696ab14adadb2e3f6c17c18ed26b3ecd96691 Mon Sep 17 00:00:00 2001
From: Oliver Hartkopp socketcan@hartkopp.net Date: Fri, 18 Jun 2021 19:36:45 +0200 Subject: [PATCH] can: gw: synchronize rcu operations before removing gw job entry
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
diff --git a/net/can/gw.c b/net/can/gw.c index ba4124805602..d8861e862f15 100644 --- a/net/can/gw.c +++ b/net/can/gw.c @@ -596,6 +596,7 @@ static int cgw_notifier(struct notifier_block *nb, 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); } } @@ -1154,6 +1155,7 @@ static void cgw_remove_all_jobs(struct net *net) 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); } } @@ -1222,6 +1224,7 @@ static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh,
hlist_del(&gwj->list); cgw_unregister_filter(net, gwj); + synchronize_rcu(); kmem_cache_free(cgw_cache, gwj); err = 0; break;