From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423328AbcE3VsT (ORCPT ); Mon, 30 May 2016 17:48:19 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52852 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162528AbcE3VAa (ORCPT ); Mon, 30 May 2016 17:00:30 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michal Nazarewicz , Lars-Peter Clausen , Felipe Balbi Subject: [PATCH 4.5 51/87] usb: gadget: f_fs: Fix EFAULT generation for async read operations Date: Mon, 30 May 2016 13:49:49 -0700 Message-Id: <20160530204935.440980516@linuxfoundation.org> X-Mailer: git-send-email 2.8.3 In-Reply-To: <20160530204933.149873142@linuxfoundation.org> References: <20160530204933.149873142@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lars-Peter Clausen commit 332a5b446b7916d272c2a659a3b20909ce34d2c1 upstream. In the current implementation functionfs generates a EFAULT for async read operations if the read buffer size is larger than the URB data size. Since a application does not necessarily know how much data the host side is going to send it typically supplies a buffer larger than the actual data, which will then result in a EFAULT error. This behaviour was introduced while refactoring the code to use iov_iter interface in commit c993c39b8639 ("gadget/function/f_fs.c: use put iov_iter into io_data"). The original code took the minimum over the URB size and the user buffer size and then attempted to copy that many bytes using copy_to_user(). If copy_to_user() could not copy all data a EFAULT error was generated. Restore the original behaviour by only generating a EFAULT error when the number of bytes copied is not the size of the URB and the target buffer has not been fully filled. Commit 342f39a6c8d3 ("usb: gadget: f_fs: fix check in read operation") already fixed the same problem for the synchronous read path. Fixes: c993c39b8639 ("gadget/function/f_fs.c: use put iov_iter into io_data") Acked-by: Michal Nazarewicz Signed-off-by: Lars-Peter Clausen Signed-off-by: Felipe Balbi Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_fs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -651,7 +651,7 @@ static void ffs_user_copy_worker(struct if (io_data->read && ret > 0) { use_mm(io_data->mm); ret = copy_to_iter(io_data->buf, ret, &io_data->data); - if (iov_iter_count(&io_data->data)) + if (ret != io_data->req->actual && iov_iter_count(&io_data->data)) ret = -EFAULT; unuse_mm(io_data->mm); }