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 X-Spam-Level: X-Spam-Status: No, score=-9.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72DECC433E4 for ; Sun, 26 Jul 2020 22:11:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E0732065F for ; Sun, 26 Jul 2020 22:11:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="qWX7qbUt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727894AbgGZWLG (ORCPT ); Sun, 26 Jul 2020 18:11:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56498 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726082AbgGZWLG (ORCPT ); Sun, 26 Jul 2020 18:11:06 -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 20780C0619D2; Sun, 26 Jul 2020 15:11:06 -0700 (PDT) Received: from pendragon.ideasonboard.com (81-175-216-236.bb.dnainternet.fi [81.175.216.236]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 6F85051D; Mon, 27 Jul 2020 00:11:04 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1595801464; bh=RjRackuP7ppvbWcf8GQqwdpQm304xRlLj+BnHq8KwrY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qWX7qbUtDABljqUxc29jNYY6LFIWwzzNovCteIYAyrBJ22N89q+e2GzcIQpzHfP2T oZ6HFGXANO1MerJUPuk6YwCymvy94eVW5a0mujqkvrPBTn8Fiy2x+K5rIOxThhKaxQ mLu3LMMbHJLGkOzwDKP2TVG4oK8KmEVNcUnYJtCI= Date: Mon, 27 Jul 2020 01:10:56 +0300 From: Laurent Pinchart To: Peilin Ye Cc: Mauro Carvalho Chehab , Greg Kroah-Hartman , syzkaller-bugs@googlegroups.com, Hans Verkuil , Sakari Ailus , Arnd Bergmann , Vandana BN , Ezequiel Garcia , Niklas =?utf-8?Q?S=C3=B6derlund?= , linux-kernel-mentees@lists.linuxfoundation.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [Linux-kernel-mentees] [PATCH v2] media/v4l2-core: Fix kernel-infoleak in video_put_user() Message-ID: <20200726221056.GJ28704@pendragon.ideasonboard.com> References: <20200726164439.48973-1-yepeilin.cs@gmail.com> <20200726220557.102300-1-yepeilin.cs@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200726220557.102300-1-yepeilin.cs@gmail.com> Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Peilin, Thank you for the patch. On Sun, Jul 26, 2020 at 06:05:57PM -0400, Peilin Ye wrote: > video_put_user() is copying uninitialized stack memory to userspace. Fix > it by initializing `ev32` and `vb32` using memset(). How about mentioning that this is caused by the compiler not initializing the holes ? Maybe something along the lines of video_put_user() is copying uninitialized stack memory to userspace due to the compiler not initializing holes in the structures declared on the stack. Fix it by initializing the structures using memset(). Reviewed-by: Laurent Pinchart > Reported-and-tested-by: syzbot+79d751604cb6f29fbf59@syzkaller.appspotmail.com > Link: https://syzkaller.appspot.com/bug?extid=79d751604cb6f29fbf59 > Signed-off-by: Peilin Ye > --- > Change in v2: > - Do the same thing for `case VIDIOC_DQEVENT_TIME32`. > > drivers/media/v4l2-core/v4l2-ioctl.c | 50 +++++++++++++++------------- > 1 file changed, 27 insertions(+), 23 deletions(-) > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c > index a556880f225a..e3a25ea913ac 100644 > --- a/drivers/media/v4l2-core/v4l2-ioctl.c > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c > @@ -3189,14 +3189,16 @@ static int video_put_user(void __user *arg, void *parg, unsigned int cmd) > #ifdef CONFIG_COMPAT_32BIT_TIME > case VIDIOC_DQEVENT_TIME32: { > struct v4l2_event *ev = parg; > - struct v4l2_event_time32 ev32 = { > - .type = ev->type, > - .pending = ev->pending, > - .sequence = ev->sequence, > - .timestamp.tv_sec = ev->timestamp.tv_sec, > - .timestamp.tv_nsec = ev->timestamp.tv_nsec, > - .id = ev->id, > - }; > + struct v4l2_event_time32 ev32; > + > + memset(&ev32, 0, sizeof(ev32)); > + > + ev32.type = ev->type; > + ev32.pending = ev->pending; > + ev32.sequence = ev->sequence; > + ev32.timestamp.tv_sec = ev->timestamp.tv_sec; > + ev32.timestamp.tv_nsec = ev->timestamp.tv_nsec; > + ev32.id = ev->id; > > memcpy(&ev32.u, &ev->u, sizeof(ev->u)); > memcpy(&ev32.reserved, &ev->reserved, sizeof(ev->reserved)); > @@ -3210,21 +3212,23 @@ static int video_put_user(void __user *arg, void *parg, unsigned int cmd) > case VIDIOC_DQBUF_TIME32: > case VIDIOC_PREPARE_BUF_TIME32: { > struct v4l2_buffer *vb = parg; > - struct v4l2_buffer_time32 vb32 = { > - .index = vb->index, > - .type = vb->type, > - .bytesused = vb->bytesused, > - .flags = vb->flags, > - .field = vb->field, > - .timestamp.tv_sec = vb->timestamp.tv_sec, > - .timestamp.tv_usec = vb->timestamp.tv_usec, > - .timecode = vb->timecode, > - .sequence = vb->sequence, > - .memory = vb->memory, > - .m.userptr = vb->m.userptr, > - .length = vb->length, > - .request_fd = vb->request_fd, > - }; > + struct v4l2_buffer_time32 vb32; > + > + memset(&vb32, 0, sizeof(vb32)); > + > + vb32.index = vb->index; > + vb32.type = vb->type; > + vb32.bytesused = vb->bytesused; > + vb32.flags = vb->flags; > + vb32.field = vb->field; > + vb32.timestamp.tv_sec = vb->timestamp.tv_sec; > + vb32.timestamp.tv_usec = vb->timestamp.tv_usec; > + vb32.timecode = vb->timecode; > + vb32.sequence = vb->sequence; > + vb32.memory = vb->memory; > + vb32.m.userptr = vb->m.userptr; > + vb32.length = vb->length; > + vb32.request_fd = vb->request_fd; > > if (copy_to_user(arg, &vb32, sizeof(vb32))) > return -EFAULT; -- Regards, Laurent Pinchart