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 24E50C433EF for ; Mon, 21 Feb 2022 08:55:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346032AbiBUIz4 (ORCPT ); Mon, 21 Feb 2022 03:55:56 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:45024 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346093AbiBUIzX (ORCPT ); Mon, 21 Feb 2022 03:55:23 -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 52B4624BC4; Mon, 21 Feb 2022 00:53:38 -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 462D761155; Mon, 21 Feb 2022 08:53:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A56CC340E9; Mon, 21 Feb 2022 08:53:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1645433612; bh=8IUsyVO3CUV/NHmrn9iyf0MiQePqG+1lN0ZMxV/tScY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mF8DOiCxxuD4Ol1jw/V0X7PMTOFQfZeKLK4+dui0R/Qvk9ASptOYqMNXFGwmQvNrX OsQ3HdIYzaID4k9Bt/x1pYJ1MR21HeD4spoYI7w8f0vzNotInhl3G3j1NLnWZ+Rv6E wIpzSeO3vl1wKlb4l8VEe+6EmVOXWAjGXXvysO7k= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Valdis=20Kl=C4=93tnieks?= , Kees Kook , "Justin M. Forbes" , Josh Poimboeuf , linux-hardening@vger.kernel.org, Arnaldo Carvalho de Melo Subject: [PATCH 4.14 26/45] libsubcmd: Fix use-after-free for realloc(..., 0) Date: Mon, 21 Feb 2022 09:49:17 +0100 Message-Id: <20220221084911.300384687@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220221084910.454824160@linuxfoundation.org> References: <20220221084910.454824160@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-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; }