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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 97329C636C8 for ; Thu, 15 Jul 2021 19:21:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 70EF6613E7 for ; Thu, 15 Jul 2021 19:21:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245134AbhGOTYA (ORCPT ); Thu, 15 Jul 2021 15:24:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:46538 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241596AbhGOTG4 (ORCPT ); Thu, 15 Jul 2021 15:06:56 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9C5C161412; Thu, 15 Jul 2021 19:03:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626375797; bh=feewwdOoKwoxjQtypCouCsjy4aJHDB7WzTa5g28dmaY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uqHHUam8YDlLcBKdXAiQJtwI7UHXSU51V+B892FOcT+avWfapD94DYCj1LZstun04 YZZSfK1fwKQThxgMlgL5HbvQR19h5gXkhmkT7OTa17sYKgbjY8qpd+ZtPoWLDuAZHF vXvbvQFCd94EatxZ0KEphuwuz7EesFHFz0KH+aYY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Arnd Bergmann , Laurent Pinchart , Hans Verkuil , Mauro Carvalho Chehab Subject: [PATCH 5.12 239/242] media: v4l2-core: explicitly clear ioctl input data Date: Thu, 15 Jul 2021 20:40:01 +0200 Message-Id: <20210715182634.914664628@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210715182551.731989182@linuxfoundation.org> References: <20210715182551.731989182@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arnd Bergmann commit 7b53cca764f9b291b7907fcd39d9e66ad728ee0b upstream. As seen from a recent syzbot bug report, mistakes in the compat ioctl implementation can lead to uninitialized kernel stack data getting used as input for driver ioctl handlers. The reported bug is now fixed, but it's possible that other related bugs are still present or get added in the future. As the drivers need to check user input already, the possible impact is fairly low, but it might still cause an information leak. To be on the safe side, always clear the entire ioctl buffer before calling the conversion handler functions that are meant to initialize them. Signed-off-by: Arnd Bergmann Reviewed-by: Laurent Pinchart Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Greg Kroah-Hartman --- drivers/media/v4l2-core/v4l2-ioctl.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/media/v4l2-core/v4l2-ioctl.c +++ b/drivers/media/v4l2-core/v4l2-ioctl.c @@ -3166,8 +3166,10 @@ static int video_get_user(void __user *a if (copy_from_user(parg, (void __user *)arg, n)) err = -EFAULT; } else if (in_compat_syscall()) { + memset(parg, 0, n); err = v4l2_compat_get_user(arg, parg, cmd); } else { + memset(parg, 0, n); #if !defined(CONFIG_64BIT) && defined(CONFIG_COMPAT_32BIT_TIME) switch (cmd) { case VIDIOC_QUERYBUF_TIME32: