netdev - [PATCH net-next] net: dsa: make user ports return to init

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 for Android: free password hash cracker in your pocket

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

Date:   Wed, 21 Sep 2022 21:54:28 +0300
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     netdev@...r.kernel.org
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Subject: [PATCH net-next] net: dsa: make user ports return to init_net on netns deletion

As pointed out during review, currently the following set of commands
crashes the kernel:

$ ip netns add ns0
$ ip link set swp0 netns ns0
$ ip netns del ns0
WARNING: CPU: 1 PID: 27 at net/core/dev.c:10884 unregister_netdevice_many+0xaa4/0xaec
Workqueue: netns cleanup_net
pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : unregister_netdevice_many+0xaa4/0xaec
lr : unregister_netdevice_many+0x700/0xaec
Call trace:
 unregister_netdevice_many+0xaa4/0xaec
 default_device_exit_batch+0x294/0x340
 ops_exit_list+0xac/0xc4
 cleanup_net+0x2e4/0x544
 process_one_work+0x4ec/0xb40
---[ end trace 0000000000000000 ]---
unregister_netdevice: waiting for swp0 to become free. Usage count = 2

This is because since DSA user ports, since they started populating
dev->rtnl_link_ops in the blamed commit, gained a different treatment
from default_device_exit_net(), which thinks these interfaces can now be
unregistered.

They can't; so set netns_refund = true to restore the behavior prior to
populating dev->rtnl_link_ops.

Fixes: 95f510d0b792 ("net: dsa: allow the DSA master to be seen and changed through rtnetlink")
Suggested-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 net/dsa/netlink.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/dsa/netlink.c b/net/dsa/netlink.c
index 0f43bbb94769..ecf9ed1de185 100644
--- a/net/dsa/netlink.c
+++ b/net/dsa/netlink.c
@@ -59,4 +59,5 @@ struct rtnl_link_ops dsa_link_ops __read_mostly = {
 	.changelink		= dsa_changelink,
 	.get_size		= dsa_get_size,
 	.fill_info		= dsa_fill_info,
+	.netns_refund		= true,
 };
-- 
2.34.1