From patchwork Mon Feb 21 08:49:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 12753280 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 5E30AC43219 for ; Mon, 21 Feb 2022 09:13:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245310AbiBUJNZ (ORCPT ); Mon, 21 Feb 2022 04:13:25 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:33874 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348842AbiBUJLp (ORCPT ); Mon, 21 Feb 2022 04:11:45 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64F8C286F3; Mon, 21 Feb 2022 01:04:14 -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 sin.source.kernel.org (Postfix) with ESMTPS id C50ECCE0E86; Mon, 21 Feb 2022 09:04:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A67F0C340E9; Mon, 21 Feb 2022 09:04:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1645434251; bh=8IUsyVO3CUV/NHmrn9iyf0MiQePqG+1lN0ZMxV/tScY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IMQx8vNcAyqO6dEGdkYG0o2lOJ238ZXCmzWgva6us1T2ykTOOZhkWTlVfE8t36RLt D/u8KlIK+mu4KNXFWtaWoFBKSoW0huw2UL3vB7uD5sWEOQ7IOyIXaXbUA32G3FpxP0 g9+1au6YlkklOU+ZVb5vjBKds5NKfv3Q2RZmPAMU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?utf-8?q?Valdis_Kl=C4=93tnieks?= , Kees Kook , "Justin M. Forbes" , Josh Poimboeuf , linux-hardening@vger.kernel.org, Arnaldo Carvalho de Melo Subject: [PATCH 5.10 065/121] libsubcmd: Fix use-after-free for realloc(..., 0) Date: Mon, 21 Feb 2022 09:49:17 +0100 Message-Id: <20220221084923.404143613@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220221084921.147454846@linuxfoundation.org> References: <20220221084921.147454846@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org From: Kees Cook commit 52a9dab6d892763b2a8334a568bd4e2c1a6fde66 upstream. GCC 12 correctly reports a potential use-after-free condition in the xrealloc helper. Fix the warning by avoiding an implicit "free(ptr)" when size == 0: In file included from help.c:12: In function 'xrealloc', inlined from 'add_cmdname' at help.c:24:2: subcmd-util.h:56:23: error: pointer may be used after 'realloc' [-Werror=use-after-free] 56 | ret = realloc(ptr, size); | ^~~~~~~~~~~~~~~~~~ subcmd-util.h:52:21: note: call to 'realloc' here 52 | void *ret = realloc(ptr, size); | ^~~~~~~~~~~~~~~~~~ subcmd-util.h:58:31: error: pointer may be used after 'realloc' [-Werror=use-after-free] 58 | ret = realloc(ptr, 1); | ^~~~~~~~~~~~~~~ subcmd-util.h:52:21: note: call to 'realloc' here 52 | void *ret = realloc(ptr, size); | ^~~~~~~~~~~~~~~~~~ Fixes: 2f4ce5ec1d447beb ("perf tools: Finalize subcmd independence") Reported-by: Valdis Klētnieks Signed-off-by: Kees Kook Tested-by: Valdis Klētnieks Tested-by: Justin M. Forbes Acked-by: Josh Poimboeuf Cc: linux-hardening@vger.kernel.org Cc: Valdis Klētnieks Link: http://lore.kernel.org/lkml/20220213182443.4037039-1-keescook@chromium.org Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Greg Kroah-Hartman --- tools/lib/subcmd/subcmd-util.h | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) --- a/tools/lib/subcmd/subcmd-util.h +++ b/tools/lib/subcmd/subcmd-util.h @@ -50,15 +50,8 @@ static NORETURN inline void die(const ch static inline void *xrealloc(void *ptr, size_t size) { void *ret = realloc(ptr, size); - if (!ret && !size) - ret = realloc(ptr, 1); - if (!ret) { - ret = realloc(ptr, size); - if (!ret && !size) - ret = realloc(ptr, 1); - if (!ret) - die("Out of memory, realloc failed"); - } + if (!ret) + die("Out of memory, realloc failed"); return ret; }