CVE-2026-23368

In the Linux kernel, the following vulnerability has been resolved:

net: phy: register phy led_triggers during probe to avoid AB-BA deadlock

There is an AB-BA deadlock when both LEDS_TRIGGER_NETDEV and

LED_TRIGGER_PHY are enabled:

[ 1362.049207] [<8054e4b8>] led_trigger_register+0x5c/0x1fc <-- Trying to get lock "triggers_list_lock" via down_write(&triggers_list_lock);

[ 1362.054536] [<80662830>] phy_led_triggers_register+0xd0/0x234

[ 1362.060329] [<8065e200>] phy_attach_direct+0x33c/0x40c

[ 1362.065489] [<80651fc4>] phylink_fwnode_phy_connect+0x15c/0x23c

[ 1362.071480] [<8066ee18>] mtk_open+0x7c/0xba0

[ 1362.075849] [<806d714c>] __dev_open+0x280/0x2b0

[ 1362.080384] [<806d7668>] __dev_change_flags+0x244/0x24c

[ 1362.085598] [<806d7698>] dev_change_flags+0x28/0x78

[ 1362.090528] [<807150e4>] dev_ioctl+0x4c0/0x654 <-- Hold lock "rtnl_mutex" by calling rtnl_lock();

[ 1362.094985] [<80694360>] sock_ioctl+0x2f4/0x4e0

[ 1362.099567] [<802e9c4c>] sys_ioctl+0x32c/0xd8c

[ 1362.104022] [<80014504>] syscall_common+0x34/0x58

Here LED_TRIGGER_PHY is registering LED triggers during phy_attach

while holding RTNL and then taking triggers_list_lock.

[ 1362.191101] [<806c2640>] register_netdevice_notifier+0x60/0x168 <-- Trying to get lock "rtnl_mutex" via rtnl_lock();

[ 1362.197073] [<805504ac>] netdev_trig_activate+0x194/0x1e4

[ 1362.202490] [<8054e28c>] led_trigger_set+0x1d4/0x360 <-- Hold lock "triggers_list_lock" by down_read(&triggers_list_lock);

[ 1362.207511] [<8054eb38>] led_trigger_write+0xd8/0x14c

[ 1362.212566] [<80381d98>] sysfs_kf_bin_write+0x80/0xbc

[ 1362.217688] [<8037fcd8>] kernfs_fop_write_iter+0x17c/0x28c

[ 1362.223174] [<802cbd70>] vfs_write+0x21c/0x3c4

[ 1362.227712] [<802cc0c4>] ksys_write+0x78/0x12c

[ 1362.232164] [<80014504>] syscall_common+0x34/0x58

Here LEDS_TRIGGER_NETDEV is being enabled on an LED. It first takes

triggers_list_lock and then RTNL. A classical AB-BA deadlock.

phy_led_triggers_registers() does not require the RTNL, it does not

make any calls into the network stack which require protection. There

is also no requirement the PHY has been attached to a MAC, the

triggers only make use of phydev state. This allows the call to

phy_led_triggers_registers() to be placed elsewhere. PHY probe() and

release() don't hold RTNL, so solving the AB-BA deadlock.