net: phy: clear phydev->devlink when the link is deleted

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: phy: clear phydev->devlink when the link is deleted There is a potential crash issue when disabling and re-enabling the network port. When disabling the network port, phy_detach() calls device_link_del() to remove the device link, but it does not clear phydev->devlink, so phydev->devlink is not a NULL pointer. Then the network port is re-enabled, but if phy_attach_direct() fails before calling device_link_add(), the code jumps to the "error" label and calls phy_detach(). Since phydev->devlink retains the old value from the previous attach/detach cycle, device_link_del() uses the old value, which accesses a NULL pointer and causes a crash. The simplified crash log is as follows. [ 24.702421] Call trace: [ 24.704856] device_link_put_kref+0x20/0x120 [ 24.709124] device_link_del+0x30/0x48 [ 24.712864] phy_detach+0x24/0x168 [ 24.716261] phy_attach_direct+0x168/0x3a4 [ 24.720352] phylink_fwnode_phy_connect+0xc8/0x14c [ 24.725140] phylink_of_phy_connect+0x1c/0x34 Therefore, phydev->devlink needs to be cleared when the device link is deleted.

References

• https://git.kernel.org/stable/c/363fdf2777423ad346d781f09548cca14877f729
• https://git.kernel.org/stable/c/ddc654e89ace723b78c34911c65243accbc9b75c
• https://git.kernel.org/stable/c/034bc4a2a72dea2cfcaf24c6bae03c38ad5a0b87
• https://git.kernel.org/stable/c/0795b05a59b1371b18ffbf09d385296b12e9f5d5