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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 15327C6786C for ; Fri, 14 Dec 2018 12:12:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE85B2133F for ; Fri, 14 Dec 2018 12:12:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544789573; bh=XfX/MPy75tFDAOzxEDwKsbJVyRvpamlSAf/pGDOJ82w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=HIBOTPah2QcgoinRZSkRelwJf09a/2QRcZgzBpISnBxaqEGcMDbDMg8Lk2AbTr1w5 t3YJEKZFqA5A8F1GJnlsQbTP7eSlUKTxePg3Xx+SHcnQUchCD/wDZFbvnTs2WQkhdc 6nyAUAdKRpM1sL5dbfJHNGfaczWR7fJKD4SJm/q4= DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BE85B2133F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732014AbeLNMMw (ORCPT ); Fri, 14 Dec 2018 07:12:52 -0500 Received: from mail.kernel.org ([198.145.29.99]:60156 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731653AbeLNMMu (ORCPT ); Fri, 14 Dec 2018 07:12:50 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E2DA320892; Fri, 14 Dec 2018 12:12:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544789569; bh=XfX/MPy75tFDAOzxEDwKsbJVyRvpamlSAf/pGDOJ82w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0EXTzpTfzy6MLEMh184+W9Y58e4gno23zkpZFMbgtSybpnKBhro2sj3dVtkyPl+J9 GGjWeOokJYJXELrZXScFlUIeT8iBnFGwwgshPbnlZelsCrfYT+7lz3QMrPzUFj52ac Qw+7eA4ayWT8ivcsK3sSr4UoQfKeXIanllVKf/bw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Artem Savkov , Josh Poimboeuf , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Sasha Levin Subject: [PATCH 4.9 22/51] objtool: Fix segfault in .cold detection with -ffunction-sections Date: Fri, 14 Dec 2018 13:00:24 +0100 Message-Id: <20181214115715.473913882@linuxfoundation.org> X-Mailer: git-send-email 2.20.0 In-Reply-To: <20181214115713.244259772@linuxfoundation.org> References: <20181214115713.244259772@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 22566c1603030f0a036ad564634b064ad1a55db2 ] Because find_symbol_by_name() traverses the same lists as read_symbols(), changing sym->name in place without copying it affects the result of find_symbol_by_name(). In the case where a ".cold" function precedes its parent in sec->symbol_list, it can result in a function being considered a parent of itself. This leads to function length being set to 0 and other consequent side-effects including a segfault in add_switch_table(). The effects of this bug are only visible when building with -ffunction-sections in KCFLAGS. Fix by copying the search string instead of modifying it in place. Signed-off-by: Artem Savkov Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Link: http://lkml.kernel.org/r/910abd6b5a4945130fd44f787c24e07b9e07c8da.1542736240.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- tools/objtool/elf.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index 3616d626991e..dd4ed7c3c062 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -31,6 +31,8 @@ #include "elf.h" #include "warn.h" +#define MAX_NAME_LEN 128 + struct section *find_section_by_name(struct elf *elf, const char *name) { struct section *sec; @@ -298,6 +300,8 @@ static int read_symbols(struct elf *elf) /* Create parent/child links for any cold subfunctions */ list_for_each_entry(sec, &elf->sections, list) { list_for_each_entry(sym, &sec->symbol_list, list) { + char pname[MAX_NAME_LEN + 1]; + size_t pnamelen; if (sym->type != STT_FUNC) continue; sym->pfunc = sym->cfunc = sym; @@ -305,9 +309,16 @@ static int read_symbols(struct elf *elf) if (!coldstr) continue; - coldstr[0] = '\0'; - pfunc = find_symbol_by_name(elf, sym->name); - coldstr[0] = '.'; + pnamelen = coldstr - sym->name; + if (pnamelen > MAX_NAME_LEN) { + WARN("%s(): parent function name exceeds maximum length of %d characters", + sym->name, MAX_NAME_LEN); + return -1; + } + + strncpy(pname, sym->name, pnamelen); + pname[pnamelen] = '\0'; + pfunc = find_symbol_by_name(elf, pname); if (!pfunc) { WARN("%s(): can't find parent function", -- 2.19.1