From: Wesley Cheng <wcheng@xxxxxxxxxxxxxx> commit 6fc1db5e6211e30fbb1cee8d7925d79d4ed2ae14 upstream. During unbind, ffs_func_eps_disable() will be executed, resulting in completion callbacks for any pending USB requests. When using AIO, irrespective of the completion status, io_data work is queued to io_completion_wq to evaluate and handle the completed requests. Since work runs asynchronously to the unbind() routine, there can be a scenario where the work runs after the USB gadget has been fully removed, resulting in accessing of a resource which has been already freed. (i.e. usb_ep_free_request() accessing the USB ep structure) Explicitly drain the io_completion_wq, instead of relying on the destroy_workqueue() (in ffs_data_put()) to make sure no pending completion work items are running. Signed-off-by: Wesley Cheng <wcheng@xxxxxxxxxxxxxx> Cc: stable <stable@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/1621644261-1236-1-git-send-email-wcheng@xxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/gadget/function/f_fs.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -3459,6 +3459,9 @@ static void ffs_func_unbind(struct usb_c ffs->func = NULL; } + /* Drain any pending AIO completions */ + drain_workqueue(ffs->io_completion_wq); + if (!--opts->refcnt) functionfs_unbind(ffs);
