[PATCH 4.19 103/196] net: bonding: correctly annotate RCU in bond_should_notify_peers()

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4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Berg <johannes.berg@xxxxxxxxx>

[ Upstream commit 3ba359c0cd6eb5ea772125a7aededb4a2d516684 ]

RCU use in bond_should_notify_peers() looks wrong, since it does
rcu_dereference(), leaves the critical section, and uses the
pointer after that.

Luckily, it's called either inside a nested RCU critical section
or with the RTNL held.

Annotate it with rcu_dereference_rtnl() instead, and remove the
inner RCU critical section.

Fixes: 4cb4f97b7e36 ("bonding: rebuild the lock use for bond_mii_monitor()")
Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Acked-by: Jay Vosburgh <jv@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20240719094119.35c62455087d.I68eb9c0f02545b364b79a59f2110f2cf5682a8e2@changeid
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/bonding/bond_main.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 79b36f1c50aec..f0c0da85ba4fc 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -774,13 +774,10 @@ static struct slave *bond_find_best_slave(struct bonding *bond)
 	return bestslave;
 }
 
+/* must be called in RCU critical section or with RTNL held */
 static bool bond_should_notify_peers(struct bonding *bond)
 {
-	struct slave *slave;
-
-	rcu_read_lock();
-	slave = rcu_dereference(bond->curr_active_slave);
-	rcu_read_unlock();
+	struct slave *slave = rcu_dereference_rtnl(bond->curr_active_slave);
 
 	if (!slave || !bond->send_peer_notif ||
 	    !netif_carrier_ok(bond->dev) ||
-- 
2.43.0







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