From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 915F4C6FA82 for ; Wed, 28 Sep 2022 20:22:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233545AbiI1UWP (ORCPT ); Wed, 28 Sep 2022 16:22:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233629AbiI1UWK (ORCPT ); Wed, 28 Sep 2022 16:22:10 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32D0A74DFD; Wed, 28 Sep 2022 13:22:01 -0700 (PDT) Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 433796BE; Wed, 28 Sep 2022 22:21:58 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1664396518; bh=ZVnn371ol3lmPTrCOy0R2eVwN8pZhNwjNTXUvUfoQqM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=O9cJMKfab+8Wu7hvOGEeJzXmby9I9rmPYVjTCDIut4xl2qcGwcltJAeye5Vc0ZNXV 7oTexktRi/HHJVw0MJ+K2+aqBhXuXl8Icia68vemMqeYHEy5jQEz2ZqYO2WjZBEhrS dnSFiRMWDucfJyWIt8uYq0sVrl2tD8PVzi1Xm8LU= Date: Wed, 28 Sep 2022 23:21:56 +0300 From: Laurent Pinchart To: Nathan Chancellor Cc: Michael Grzeschik , Felipe Balbi , Greg Kroah-Hartman , Kees Cook , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, stable@vger.kernel.org Subject: Re: [PATCH] usb: gadget: uvc: Fix argument to sizeof() in uvc_register_video() Message-ID: References: <20220928201921.3152163-1-nathan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220928201921.3152163-1-nathan@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Nathan, Thank you for the patch. On Wed, Sep 28, 2022 at 01:19:21PM -0700, Nathan Chancellor wrote: > When building s390 allmodconfig after commit 9b91a6523078 ("usb: gadget: > uvc: increase worker prio to WQ_HIGHPRI"), the following error occurs: > > In file included from ../include/linux/string.h:253, > from ../include/linux/bitmap.h:11, > from ../include/linux/cpumask.h:12, > from ../include/linux/smp.h:13, > from ../include/linux/lockdep.h:14, > from ../include/linux/rcupdate.h:29, > from ../include/linux/rculist.h:11, > from ../include/linux/pid.h:5, > from ../include/linux/sched.h:14, > from ../include/linux/ratelimit.h:6, > from ../include/linux/dev_printk.h:16, > from ../include/linux/device.h:15, > from ../drivers/usb/gadget/function/f_uvc.c:9: > In function ‘fortify_memset_chk’, > inlined from ‘uvc_register_video’ at ../drivers/usb/gadget/function/f_uvc.c:424:2: > ../include/linux/fortify-string.h:301:25: error: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning] > 301 | __write_overflow_field(p_size_field, size); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > This points to the memset() in uvc_register_video(). It is clear that > the argument to sizeof() is incorrect, as uvc->vdev (a 'struct > video_device') is being zeroed out but the size of uvc->video (a 'struct > uvc_video') is being used as the third arugment to memset(). > > pahole shows that prior to commit 9b91a6523078 ("usb: gadget: uvc: > increase worker prio to WQ_HIGHPRI"), 'struct video_device' and > 'struct ucv_video' had the same size, meaning that the argument to > sizeof() is incorrect semantically but there is no visible issue: > > $ pahole -s build/drivers/usb/gadget/function/f_uvc.o | grep -E "(uvc_video|video_device)\s+" > video_device 1400 4 > uvc_video 1400 3 > > After that change, uvc_video becomes slightly larger, meaning that the > memset() will overwrite by 8 bytes: > > $ pahole -s build/drivers/usb/gadget/function/f_uvc.o | grep -E "(uvc_video|video_device)\s+" > video_device 1400 4 > uvc_video 1408 3 > > Fix the arugment to sizeof() so that there is no overwrite. > > Cc: stable@vger.kernel.org > Fixes: e4ce9ed835bc ("usb: gadget: uvc: ensure the vdev is unset") > Signed-off-by: Nathan Chancellor Good catch. Reviewed-by: Laurent Pinchart > --- > drivers/usb/gadget/function/f_uvc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c > index 71669e0e4d00..86bb0098fb66 100644 > --- a/drivers/usb/gadget/function/f_uvc.c > +++ b/drivers/usb/gadget/function/f_uvc.c > @@ -421,7 +421,7 @@ uvc_register_video(struct uvc_device *uvc) > int ret; > > /* TODO reference counting. */ > - memset(&uvc->vdev, 0, sizeof(uvc->video)); > + memset(&uvc->vdev, 0, sizeof(uvc->vdev)); > uvc->vdev.v4l2_dev = &uvc->v4l2_dev; > uvc->vdev.v4l2_dev->dev = &cdev->gadget->dev; > uvc->vdev.fops = &uvc_v4l2_fops; > > base-commit: f76349cf41451c5c42a99f18a9163377e4b364ff -- Regards, Laurent Pinchart