published December 8, 2025
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_fs: Fix epfile null pointer access after ep enable.
A race condition occurs when ffs_func_eps_enable() runs concurrently
with ffs_data_reset(). The ffs_data_clear() called in ffs_data_reset()
sets ffs->epfiles to NULL before resetting ffs->eps_count to 0, leading
to a NULL pointer dereference when accessing epfile->ep in
ffs_func_eps_enable() after successful usb_ep_enable().
The ffs->epfiles pointer is set to NULL in both ffs_data_clear() and
ffs_data_close() functions, and its modification is protected by the
spinlock ffs->eps_lock. And the whole ffs_func_eps_enable() function
is also protected by ffs->eps_lock.
Thus, add NULL pointer handling for ffs->epfiles in the
ffs_func_eps_enable() function to fix issues