In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_tcm: fix deadlock in usbg_make_tpg()
usbg_make_tpg() held dep_lock while calling
configfs_depend_item_unlocked(), which acquires the configfs root
inode lock when operating across subsystems. This creates a circular
lock dependency with configfs_rmdir():
dep_lock -> configfs root inode lock -> su_mutex -> dep_lock
In usbg_make_tpg(), dep_lock only serialized the read of opts->ready,
which is a monotonic flag that transitions from false to true exactly
once (in tcm_set_name()) and never reverts. Remove dep_lock from
usbg_make_tpg() entirely and use READ_ONCE/WRITE_ONCE to access
opts->ready locklessly instead.
