From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752956AbdLLMr2 (ORCPT ); Tue, 12 Dec 2017 07:47:28 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:58986 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752874AbdLLMrR (ORCPT ); Tue, 12 Dec 2017 07:47:17 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, John Keeping , Felipe Balbi Subject: [PATCH 4.14 006/164] usb: f_fs: Force Reserved1=1 in OS_DESC_EXT_COMPAT Date: Tue, 12 Dec 2017 13:43:06 +0100 Message-Id: <20171212123444.107595718@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171212123443.785979602@linuxfoundation.org> References: <20171212123443.785979602@linuxfoundation.org> User-Agent: quilt/0.65 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 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: John Keeping commit a3acc696085e112733d191a77b106e67a4fa110b upstream. The specification says that the Reserved1 field in OS_DESC_EXT_COMPAT must have the value "1", but when this feature was first implemented we rejected any non-zero values. This was adjusted to accept all non-zero values (while now rejecting zero) in commit 53642399aa71 ("usb: gadget: f_fs: Fix wrong check on reserved1 of OS_DESC_EXT_COMPAT"), but that breaks any userspace programs that worked previously by returning EINVAL when Reserved1 == 0 which was previously the only value that succeeded! If we just set the field to "1" ourselves, both old and new userspace programs continue to work correctly and, as a bonus, old programs are now compliant with the specification without having to fix anything themselves. Fixes: 53642399aa71 ("usb: gadget: f_fs: Fix wrong check on reserved1 of OS_DESC_EXT_COMPAT") Signed-off-by: John Keeping Signed-off-by: Felipe Balbi Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_fs.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -2286,9 +2286,18 @@ static int __ffs_data_do_os_desc(enum ff int i; if (len < sizeof(*d) || - d->bFirstInterfaceNumber >= ffs->interfaces_count || - !d->Reserved1) + d->bFirstInterfaceNumber >= ffs->interfaces_count) return -EINVAL; + if (d->Reserved1 != 1) { + /* + * According to the spec, Reserved1 must be set to 1 + * but older kernels incorrectly rejected non-zero + * values. We fix it here to avoid returning EINVAL + * in response to values we used to accept. + */ + pr_debug("usb_ext_compat_desc::Reserved1 forced to 1\n"); + d->Reserved1 = 1; + } for (i = 0; i < ARRAY_SIZE(d->Reserved2); ++i) if (d->Reserved2[i]) return -EINVAL;