linux-kernel - [PATCH AUTOSEL 4.9 04/17] bonding: init notify

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Message-Id: <20210603171052.3169893-4-sashal@kernel.org>
Date:   Thu,  3 Jun 2021 13:10:39 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Johannes Berg <johannes.berg@...el.com>,
        syzbot+bfda097c12a00c8cae67@...kaller.appspotmail.com,
        Jay Vosburgh <jay.vosburgh@...onical.com>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.9 04/17] bonding: init notify_work earlier to avoid uninitialized use

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

[ Upstream commit 35d96e631860226d5dc4de0fad0a415362ec2457 ]

If bond_kobj_init() or later kzalloc() in bond_alloc_slave() fail,
then we call kobject_put() on the slave->kobj. This in turn calls
the release function slave_kobj_release() which will always try to
cancel_delayed_work_sync(&slave->notify_work), which shouldn't be
done on an uninitialized work struct.

Always initialize the work struct earlier to avoid problems here.

Syzbot bisected this down to a completely pointless commit, some
fault injection may have been at work here that caused the alloc
failure in the first place, which may interact badly with bisect.

Reported-by: syzbot+bfda097c12a00c8cae67@...kaller.appspotmail.com
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Acked-by: Jay Vosburgh <jay.vosburgh@...onical.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/bonding/bond_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 16437aa35bc4..2b721ed392ad 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1280,6 +1280,7 @@ static struct slave *bond_alloc_slave(struct bonding *bond,
 
 	slave->bond = bond;
 	slave->dev = slave_dev;
+	INIT_DELAYED_WORK(&slave->notify_work, bond_netdev_notify_work);
 
 	if (bond_kobj_init(slave))
 		return NULL;
@@ -1292,7 +1293,6 @@ static struct slave *bond_alloc_slave(struct bonding *bond,
 			return NULL;
 		}
 	}
-	INIT_DELAYED_WORK(&slave->notify_work, bond_netdev_notify_work);
 
 	return slave;
 }
-- 
2.30.2