From: Owen Gu guhuinan@xiaomi.com
[ Upstream commit cfd6f1a7b42f ("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
Signed-off-by: Owen Gu guhuinan@xiaomi.com Link: https://lore.kernel.org/r/20250915092907.17802-1-guhuinan@xiaomi.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/gadget/function/f_fs.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 08a251df20c4..04058261cdd0 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -2407,7 +2407,12 @@ static int ffs_func_eps_enable(struct ffs_function *func) ep = func->eps; epfile = ffs->epfiles; count = ffs->eps_count; - while(count--) { + if (!epfile) { + ret = -ENOMEM; + goto done; + } + + while (count--) { ep->ep->driver_data = ep;
ret = config_ep_by_speed(func->gadget, &func->function, ep->ep); @@ -2431,6 +2436,7 @@ static int ffs_func_eps_enable(struct ffs_function *func) }
wake_up_interruptible(&ffs->wait); +done: spin_unlock_irqrestore(&func->ffs->eps_lock, flags);
return ret;