Path: csiph.com!1.us.feeder.erje.net!feeder.erje.net!2.eu.feeder.erje.net!news.unit0.net!news.panservice.it!bofh.it!news.nic.it!robomod From: Greg Kroah-Hartman Newsgroups: linux.kernel Subject: [PATCH 4.4 51/86] usb: gadget: f_fs: Fix EFAULT generation for async read operations Date: Tue, 31 May 2016 00:00:03 +0200 Message-ID: References: X-Original-To: linux-kernel@vger.kernel.org X-Mailer: git-send-email 2.8.3 User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: robomod@news.nic.it List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Approved: robomod@news.nic.it Lines: 47 Organization: linux.* mail to news gateway X-Original-Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michal Nazarewicz , Lars-Peter Clausen , Felipe Balbi X-Original-Date: Mon, 30 May 2016 13:49:40 -0700 X-Original-Message-ID: <20160530204939.150558967@linuxfoundation.org> X-Original-References: <20160530204937.379068148@linuxfoundation.org> X-Original-Sender: linux-kernel-owner@vger.kernel.org Xref: csiph.com linux.kernel:1409627 4.4-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); }