Wind River Support Network

Description

In the Linux kernel, the following vulnerability has been resolved:[EOL][EOL]usb: gadget: udc: fix use-after-free in usb_gadget_state_work[EOL][EOL]A race condition during gadget teardown can lead to a use-after-free[EOL]in usb_gadget_state_work(), as reported by KASAN:[EOL][EOL]  BUG: KASAN: invalid-access in sysfs_notify+0x2c/0xd0[EOL]  Workqueue: events usb_gadget_state_work[EOL][EOL]The fundamental race occurs because a concurrent event (e.g., an[EOL]interrupt) can call usb_gadget_set_state() and schedule gadget->work[EOL]at any time during the cleanup process in usb_del_gadget().[EOL][EOL]Commit 399a45e5237c ("usb: gadget: core: flush gadget workqueue after[EOL]device removal") attempted to fix this by moving flush_work() to after[EOL]device_del(). However, this does not fully solve the race, as a new[EOL]work item can still be scheduled *after* flush_work() completes but[EOL]before the gadget's memory is freed, leading to the same use-after-free.[EOL][EOL]This patch fixes the race condition robustly by introducing a 'teardown'[EOL]flag and a 'state_lock' spinlock to the usb_gadget struct. The flag is[EOL]set during cleanup in usb_del_gadget() *before* calling flush_work() to[EOL]prevent any new work from being scheduled once cleanup has commenced.[EOL]The scheduling site, usb_gadget_set_state(), now checks this flag under[EOL]the lock before queueing the work, thus safely closing the race window.