5.4-stable review patch. If anyone has any objections, please let me know.
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From: Owen Gu guhuinan@xiaomi.com
commit cfd6f1a7b42f62523c96d9703ef32b0dbc495ba4 upstream.
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(-)
--- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -2012,7 +2012,12 @@ static int ffs_func_eps_enable(struct ff 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); @@ -2036,6 +2041,7 @@ static int ffs_func_eps_enable(struct ff }
wake_up_interruptible(&ffs->wait); +done: spin_unlock_irqrestore(&func->ffs->eps_lock, flags);
return ret;