netdev - [PATCH net] net: bridge: fix net device refcount tracking issue in error path

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]

Date:   Wed, 12 Jan 2022 04:53:00 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        syzbot <syzkaller@...glegroups.com>
Subject: [PATCH net] net: bridge: fix net device refcount tracking issue in error path

From: Eric Dumazet <edumazet@...gle.com>

I left one dev_put() in br_add_if() error path and sure enough
syzbot found its way.

As the tracker is allocated in new_nbp(), we must make sure
to properly free it.

We have to call dev_put_track(dev, &p->dev_tracker) before
@p object is freed, of course. This is not an issue because
br_add_if() owns a reference on @dev.

Fixes: b2dcdc7f731d ("net: bridge: add net device refcount tracker")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: syzbot <syzkaller@...glegroups.com>
---
 net/bridge/br_if.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index a52ad81596b72dde8e9a0affccd38c91ab59315d..55f47cadb114038920c01bf43e43500e07a3539c 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -615,6 +615,7 @@ int br_add_if(struct net_bridge *br, struct net_device *dev,
 	err = dev_set_allmulti(dev, 1);
 	if (err) {
 		br_multicast_del_port(p);
+		dev_put_track(dev, &p->dev_tracker);
 		kfree(p);	/* kobject not yet init'd, manually free */
 		goto err1;
 	}
@@ -724,10 +725,10 @@ int br_add_if(struct net_bridge *br, struct net_device *dev,
 	sysfs_remove_link(br->ifobj, p->dev->name);
 err2:
 	br_multicast_del_port(p);
+	dev_put_track(dev, &p->dev_tracker);
 	kobject_put(&p->kobj);
 	dev_set_allmulti(dev, -1);
 err1:
-	dev_put(dev);
 	return err;
 }
 
-- 
2.34.1.575.g55b058a8bb-goog