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FAILED: patch "[PATCH] can: gw: synchronize rcu operations before removing gw job" failed to apply to 4.9-stable tree

PATCH [email protected] 1 participant 1 message Jul 11, 2021

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Stable branch CAN network layer
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The patch below does not apply to the 4.9-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 <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From fb8696ab14adadb2e3f6c17c18ed26b3ecd96691 Mon Sep 17 00:00:00 2001
From: Oliver Hartkopp <[email protected]>
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/[email protected] open here
Fixes c1aabdf379bc ("can-gw: add netlink based CAN routing")
Cc linux-stable <[email protected]>
Signed-off-by Oliver Hartkopp <[email protected]>
Signed-off-by Marc Kleine-Budde <[email protected]>
net/can/gw.c +3 -0
index ba4124805602..d8861e862f15 100644
@@ -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;