Description

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] [] led_trigger_register+0x5c/0x1fc <-- Trying to get lock "triggers_list_lock" via down_write(&triggers_list_lock); [ 1362.054536] [] phy_led_triggers_register+0xd0/0x234 [ 1362.060329] [] phy_attach_direct+0x33c/0x40c [ 1362.065489] [] phylink_fwnode_phy_connect+0x15c/0x23c [ 1362.071480] [] mtk_open+0x7c/0xba0 [ 1362.075849] [] __dev_open+0x280/0x2b0 [ 1362.080384] [] __dev_change_flags+0x244/0x24c [ 1362.085598] [] dev_change_flags+0x28/0x78 [ 1362.090528] [] dev_ioctl+0x4c0/0x654 <-- Hold lock "rtnl_mutex" by calling rtnl_lock(); [ 1362.094985] [] sock_ioctl+0x2f4/0x4e0 [ 1362.099567] [] sys_ioctl+0x32c/0xd8c [ 1362.104022] [] 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] [] register_netdevice_notifier+0x60/0x168 <-- Trying to get lock "rtnl_mutex" via rtnl_lock(); [ 1362.197073] [] netdev_trig_activate+0x194/0x1e4 [ 1362.202490] [] led_trigger_set+0x1d4/0x360 <-- Hold lock "triggers_list_lock" by down_read(&triggers_list_lock); [ 1362.207511] [] led_trigger_write+0xd8/0x14c [ 1362.212566] [] sysfs_kf_bin_write+0x80/0xbc [ 1362.217688] [] kernfs_fop_write_iter+0x17c/0x28c [ 1362.223174] [] vfs_write+0x21c/0x3c4 [ 1362.227712] [] ksys_write+0x78/0x12c [ 1362.232164] [] 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.

Severity Medium

CVSS Score 5.5

CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CWE N/A

Public Exploit ✅ No

Source NVD

Published 2026-03-25

Updated 2026-06-05

Modified 2026-06-04

Fix URL https://git.kernel.org/stable/c/241cd64cf2e32b28ead151b1795cd8fef2b6e482

Software	From version	Fixed in
kernel	6.19.0	6.19.7
linux-kernel	—	—