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 D4E9DC64ED6 for ; Sun, 26 Feb 2023 14:53:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230170AbjBZOx3 (ORCPT ); Sun, 26 Feb 2023 09:53:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229905AbjBZOwq (ORCPT ); Sun, 26 Feb 2023 09:52:46 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D3AC01A4AC; Sun, 26 Feb 2023 06:49:31 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 79C1B60C73; Sun, 26 Feb 2023 14:48:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5457FC433EF; Sun, 26 Feb 2023 14:48:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677422892; bh=k+/A8QkvwlsTflil4hhu/Jphf8ICYteEj1VK1FUV0i0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iR3TYIi1h9HWo14lxhRCvckAflzwK5TSm0NHcrRvT6v0CbqYwm09BOWma1MBBzTdw PWY7IBTipN3WAB9/aWWe50mYNpVrJfW95B8qIxAJWdckJ1r87VIB5bMhKZ87F2lVx4 sjBf0Qg+coEnzTbE8DIGel1JtB8/WJbpY8icUzih6A9nH/5tnczz0WH8YQcdjnu6QG K7vjyYajl5buaBuW1ELnAvOCgXS2QMbEQI5Lw/sJBeU7oqHpFgmtbkYfYrW4VsRuF6 mlEZtrTN+nZlis+N0L80nSEmetlGMRDF8Q1Vtuy/JHiSRxVYMTrNTYre3fu6pNqUXb H637KokoNfSdA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kees Cook , Christian Brauner , Rasmus Villemoes , Arnd Bergmann , Dinh Nguyen , Catalin Marinas , Andrew Morton , Geert Uytterhoeven , Alexander Potapenko , Aleksa Sarai , Sasha Levin , elver@google.com, christophe.leroy@csgroup.eu, viro@zeniv.linux.org.uk Subject: [PATCH AUTOSEL 6.1 36/49] uaccess: Add minimum bounds check on kernel buffer size Date: Sun, 26 Feb 2023 09:46:36 -0500 Message-Id: <20230226144650.826470-36-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230226144650.826470-1-sashal@kernel.org> References: <20230226144650.826470-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kees Cook [ Upstream commit 04ffde1319a715bd0550ded3580d4ea3bc003776 ] While there is logic about the difference between ksize and usize, copy_struct_from_user() didn't check the size of the destination buffer (when it was known) against ksize. Add this check so there is an upper bounds check on the possible memset() call, otherwise lower bounds checks made by callers will trigger bounds warnings under -Warray-bounds. Seen under GCC 13: In function 'copy_struct_from_user', inlined from 'iommufd_fops_ioctl' at ../drivers/iommu/iommufd/main.c:333:8: ../include/linux/fortify-string.h:59:33: warning: '__builtin_memset' offset [57, 4294967294] is out of the bounds [0, 56] of object 'buf' with type 'union ucmd_buffer' [-Warray-bounds=] 59 | #define __underlying_memset __builtin_memset | ^ ../include/linux/fortify-string.h:453:9: note: in expansion of macro '__underlying_memset' 453 | __underlying_memset(p, c, __fortify_size); \ | ^~~~~~~~~~~~~~~~~~~ ../include/linux/fortify-string.h:461:25: note: in expansion of macro '__fortify_memset_chk' 461 | #define memset(p, c, s) __fortify_memset_chk(p, c, s, \ | ^~~~~~~~~~~~~~~~~~~~ ../include/linux/uaccess.h:334:17: note: in expansion of macro 'memset' 334 | memset(dst + size, 0, rest); | ^~~~~~ ../drivers/iommu/iommufd/main.c: In function 'iommufd_fops_ioctl': ../drivers/iommu/iommufd/main.c:311:27: note: 'buf' declared here 311 | union ucmd_buffer buf; | ^~~ Cc: Christian Brauner Cc: Rasmus Villemoes Cc: Arnd Bergmann Cc: Dinh Nguyen Cc: Catalin Marinas Cc: Andrew Morton Cc: Geert Uytterhoeven Cc: Alexander Potapenko Acked-by: Aleksa Sarai Signed-off-by: Kees Cook Link: https://lore.kernel.org/lkml/20230203193523.never.667-kees@kernel.org/ Signed-off-by: Sasha Levin --- include/linux/uaccess.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index afb18f198843b..ab9728138ad67 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -329,6 +329,10 @@ copy_struct_from_user(void *dst, size_t ksize, const void __user *src, size_t size = min(ksize, usize); size_t rest = max(ksize, usize) - size; + /* Double check if ksize is larger than a known object size. */ + if (WARN_ON_ONCE(ksize > __builtin_object_size(dst, 1))) + return -E2BIG; + /* Deal with trailing bytes. */ if (usize < ksize) { memset(dst + size, 0, rest); -- 2.39.0