6.16-stable review patch. If anyone has any objections, please let me know.
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From: Stanislav Fomichev sdf@fomichev.me
[ Upstream commit 53898ebabe843bfa7baea9dae152797d5d0563c9 ]
Syzkaller managed to trigger lock dependency in xsk_notify via register_netdevice. As discussed in [0], using register_netdevice in the notifiers is problematic so skip adding lapbeth for ops-locked devices.
xsk_notifier+0xa4/0x280 net/xdp/xsk.c:1645 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2230 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline] call_netdevice_notifiers net/core/dev.c:2282 [inline] unregister_netdevice_many_notify+0xf9d/0x2700 net/core/dev.c:12077 unregister_netdevice_many net/core/dev.c:12140 [inline] unregister_netdevice_queue+0x305/0x3f0 net/core/dev.c:11984 register_netdevice+0x18f1/0x2270 net/core/dev.c:11149 lapbeth_new_device drivers/net/wan/lapbether.c:420 [inline] lapbeth_device_event+0x5b1/0xbe0 drivers/net/wan/lapbether.c:462 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2230 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline] call_netdevice_notifiers net/core/dev.c:2282 [inline] __dev_notify_flags+0x12c/0x2e0 net/core/dev.c:9497 netif_change_flags+0x108/0x160 net/core/dev.c:9526 dev_change_flags+0xba/0x250 net/core/dev_api.c:68 devinet_ioctl+0x11d5/0x1f50 net/ipv4/devinet.c:1200 inet_ioctl+0x3a7/0x3f0 net/ipv4/af_inet.c:1001
0: https://lore.kernel.org/netdev/20250625140357.6203d0af@kernel.org/ Fixes: 4c975fd70002 ("net: hold instance lock during NETDEV_REGISTER/UP") Suggested-by: Jakub Kicinski kuba@kernel.org Reported-by: syzbot+e67ea9c235b13b4f0020@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=e67ea9c235b13b4f0020 Signed-off-by: Stanislav Fomichev sdf@fomichev.me Link: https://patch.msgid.link/20250806213726.1383379-1-sdf@fomichev.me Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/wan/lapbether.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c index 995a7207bdf8..f357a7ac70ac 100644 --- a/drivers/net/wan/lapbether.c +++ b/drivers/net/wan/lapbether.c @@ -81,7 +81,7 @@ static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
static __inline__ int dev_is_ethdev(struct net_device *dev) { - return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5); + return dev->type == ARPHRD_ETHER && !netdev_need_ops_lock(dev); }
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