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] [<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.
Product status
06f502f57d0d7728f9fa0f157ec5e4111ddb98f6 (git) before 2b01518eabace18f7ec8b4cafd52082303080dca
06f502f57d0d7728f9fa0f157ec5e4111ddb98f6 (git) before 305afdd02ff3e694c165457793104710ec0728e5
06f502f57d0d7728f9fa0f157ec5e4111ddb98f6 (git) before c6ffc2d2338d325e1edd0c702e3ee623aa5fdc6a
06f502f57d0d7728f9fa0f157ec5e4111ddb98f6 (git) before c33523b8fd2d4c504ada18cd93f511f2a8f84217
06f502f57d0d7728f9fa0f157ec5e4111ddb98f6 (git) before 241cd64cf2e32b28ead151b1795cd8fef2b6e482
06f502f57d0d7728f9fa0f157ec5e4111ddb98f6 (git) before 2764dcb3c35de4410f642afc62cf979727470575
06f502f57d0d7728f9fa0f157ec5e4111ddb98f6 (git) before cde2d0b5ab5d03b5b6f17d4f654d8b30ccf36757
06f502f57d0d7728f9fa0f157ec5e4111ddb98f6 (git) before c8dbdc6e380e7e96a51706db3e4b7870d8a9402d
4.16
Any version before 4.16
5.10.253 (semver)
5.15.203 (semver)
6.1.167 (semver)
6.6.130 (semver)
6.12.78 (semver)
6.18.17 (semver)
6.19.7 (semver)
7.0 (original_commit_for_fix)
References
git.kernel.org/...c/2b01518eabace18f7ec8b4cafd52082303080dca
git.kernel.org/...c/305afdd02ff3e694c165457793104710ec0728e5
git.kernel.org/...c/c6ffc2d2338d325e1edd0c702e3ee623aa5fdc6a
git.kernel.org/...c/c33523b8fd2d4c504ada18cd93f511f2a8f84217
git.kernel.org/...c/241cd64cf2e32b28ead151b1795cd8fef2b6e482
git.kernel.org/...c/2764dcb3c35de4410f642afc62cf979727470575
git.kernel.org/...c/cde2d0b5ab5d03b5b6f17d4f654d8b30ccf36757
git.kernel.org/...c/c8dbdc6e380e7e96a51706db3e4b7870d8a9402d