netdev - [RFC PATCH 1/2] net: bonding: correctly annotate RCU in bond_should_notify

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240718122017.b1051af4e7f7.I68eb9c0f02545b364b79a59f2110f2cf5682a8e2@changeid>
Date: Thu, 18 Jul 2024 12:20:16 -0700
From: Johannes Berg <johannes@...solutions.net>
To: netdev@...r.kernel.org
Cc: Eric Dumazet <edumazet@...gle.com>,
	Johannes Berg <johannes.berg@...el.com>
Subject: [RFC PATCH 1/2] net: bonding: correctly annotate RCU in bond_should_notify_peers()

From: Johannes Berg <johannes.berg@...el.com>

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.

Signed-off-by: Johannes Berg <johannes.berg@...el.com>
---
 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 d19aabf5d4fb..2ed0da068490 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1121,13 +1121,10 @@ 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 ||
 	    bond->send_peer_notif %
-- 
2.45.2