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 D3039C64ED6 for ; Sun, 26 Feb 2023 15:09:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229841AbjBZPJ0 (ORCPT ); Sun, 26 Feb 2023 10:09:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53306 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231791AbjBZPIv (ORCPT ); Sun, 26 Feb 2023 10:08:51 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3E72722791; Sun, 26 Feb 2023 06:59:12 -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 736B560C7C; Sun, 26 Feb 2023 14:49:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F5FDC433A0; Sun, 26 Feb 2023 14:49:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677422994; bh=TA+Tz1v7hXIMLtsleefusQBWDuSOjj4AUYxaP/0UQJA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qEkHBSFmzfFPwzLQvR2SCIJD9XSn6evYFE9jtJd91Sh+V/P675LSz5lY7ZiLVXpu5 20R2xp5nBrrj5+3mWe921rMgusU+qaYFgSe7f6HwWzMROFoVv4ttU52PmolZfEyTqu fspAk2TfsFrucia/iWw5lnRZVBEOt2DfOCPNdclvwm+8qLyPgPMb9lq1I7+tZt2nWl M8bvjkGlbG9ODUkoll+f+lxtEWZqujkybRmblXgM9Ee0xYJbxri82Tu0SxEuB0x76c CuEYHhvAwWoz3AumCSz7HdQKOkAyX7NiSrXdP/+up9Cn5gR4GXYyXXVZ3tmxeq471j PfZJh32oCSIEw== 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 , linmiaohe@huawei.com, viro@zeniv.linux.org.uk, christophe.leroy@csgroup.eu Subject: [PATCH AUTOSEL 5.15 28/36] uaccess: Add minimum bounds check on kernel buffer size Date: Sun, 26 Feb 2023 09:48:36 -0500 Message-Id: <20230226144845.827893-28-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230226144845.827893-1-sashal@kernel.org> References: <20230226144845.827893-1-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 ac0394087f7d4..e1d59ca6530da 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -338,6 +338,10 @@ 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