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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 43F00C5B57D for ; Wed, 3 Jul 2019 02:17:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1A6B821873 for ; Wed, 3 Jul 2019 02:17:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562120255; bh=7NiTt5czzUH551Nzj8LZqum/G+FC9dq30qWS4x1U9kE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jNTxYF2X2OzUcvXsBdqHN5dxNt/a46qfzGjFfhCC9IX4mD7kYjCuUyaxbNfYTnAYT 6rz0s5jC11AHySgHczIBWM1x2evdN4oNchSHT/2mdELrzkyOLxMbxMqumDgVjrvamC ch2FN+sn7weuUeRHONU0F86KzaiMsuNmSXSNFKBs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728186AbfGCCRd (ORCPT ); Tue, 2 Jul 2019 22:17:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:55208 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728054AbfGCCQs (ORCPT ); Tue, 2 Jul 2019 22:16:48 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DC8D221880; Wed, 3 Jul 2019 02:16:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562120207; bh=7NiTt5czzUH551Nzj8LZqum/G+FC9dq30qWS4x1U9kE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ArZs3jdXXUupmbULP0h9BR2bRDgccGB0Yt5rGZjkcSzONYUM7LTKRkCURjrg0lsGn l8uYDWHROPQtzs96K9+661KPLC3HrSQnkzDllFd2y+e7/MZ2EkUKqE023/CQeVb2Al RldlclbKvMxZ3klfsrXKj7SdUjky/JcmCfuierjQ= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jerome Marchand , Mike Snitzer , Sasha Levin Subject: [PATCH AUTOSEL 4.19 17/26] dm table: don't copy from a NULL pointer in realloc_argv() Date: Tue, 2 Jul 2019 22:16:16 -0400 Message-Id: <20190703021625.18116-17-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190703021625.18116-1-sashal@kernel.org> References: <20190703021625.18116-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jerome Marchand [ Upstream commit a0651926553cfe7992166432e418987760882652 ] For the first call to realloc_argv() in dm_split_args(), old_argv is NULL and size is zero. Then memcpy is called, with the NULL old_argv as the source argument and a zero size argument. AFAIK, this is undefined behavior and generates the following warning when compiled with UBSAN on ppc64le: In file included from ./arch/powerpc/include/asm/paca.h:19, from ./arch/powerpc/include/asm/current.h:16, from ./include/linux/sched.h:12, from ./include/linux/kthread.h:6, from drivers/md/dm-core.h:12, from drivers/md/dm-table.c:8: In function 'memcpy', inlined from 'realloc_argv' at drivers/md/dm-table.c:565:3, inlined from 'dm_split_args' at drivers/md/dm-table.c:588:9: ./include/linux/string.h:345:9: error: argument 2 null where non-null expected [-Werror=nonnull] return __builtin_memcpy(p, q, size); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/md/dm-table.c: In function 'dm_split_args': ./include/linux/string.h:345:9: note: in a call to built-in function '__builtin_memcpy' Signed-off-by: Jerome Marchand Signed-off-by: Mike Snitzer Signed-off-by: Sasha Levin --- drivers/md/dm-table.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index c7fe4789c40e..34ab30dd5de9 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -562,7 +562,7 @@ static char **realloc_argv(unsigned *size, char **old_argv) gfp = GFP_NOIO; } argv = kmalloc_array(new_size, sizeof(*argv), gfp); - if (argv) { + if (argv && old_argv) { memcpy(argv, old_argv, *size * sizeof(*argv)); *size = new_size; } -- 2.20.1