From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 63951 invoked by alias); 27 Aug 2018 14:57:33 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 63227 invoked by uid 89); 27 Aug 2018 14:57:06 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,RCVD_IN_DNSWL_NONE,SPF_HELO_PASS,TIME_LIMIT_EXCEEDED autolearn=unavailable version=3.3.2 spammy=leb X-HELO: gateway22.websitewelcome.com Received: from gateway22.websitewelcome.com (HELO gateway22.websitewelcome.com) (192.185.47.206) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 27 Aug 2018 14:56:28 +0000 Received: from cm11.websitewelcome.com (cm11.websitewelcome.com [100.42.49.5]) by gateway22.websitewelcome.com (Postfix) with ESMTP id 20426118E2 for ; Mon, 27 Aug 2018 09:56:27 -0500 (CDT) Received: from box5379.bluehost.com ([162.241.216.53]) by cmsmtp with SMTP id uIwNfyHS2RPojuIwNfOfDU; Mon, 27 Aug 2018 09:56:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=tromey.com; s=default; h=References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Sender:Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=jIKgjj92N6OamUkXj7RBaEbyzhhgIaA74+K4MGFQf/k=; b=Z/GMgSdIYHJZ7rWp8CBGsklmhd 4nZteuYCJsdLOYPG1nipixPBZ/Tgtk+r366M9HjFB3j4phfI3/ji4pHST9Q/ky1Z/vujtBpL9Y9sU hArR20M9bc/+Vf43YFZES6SPm; Received: from 75-166-85-72.hlrn.qwest.net ([75.166.85.72]:54030 helo=bapiya.Home) by box5379.bluehost.com with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91) (envelope-from ) id 1fuIwM-000csy-Qi; Mon, 27 Aug 2018 09:56:26 -0500 From: Tom Tromey To: gdb-patches@sourceware.org Cc: Tom Tromey Subject: [PATCH 6/9] Avoid undefined behavior in read_signed_leb128 Date: Mon, 27 Aug 2018 14:57:00 -0000 Message-Id: <20180827145620.11055-7-tom@tromey.com> In-Reply-To: <20180827145620.11055-1-tom@tromey.com> References: <20180827145620.11055-1-tom@tromey.com> X-SW-Source: 2018-08/txt/msg00651.txt.bz2 -fsanitize=undefined pointed out that read_signed_leb128 had an undefined left-shift when processing the final byte of a 64-bit leb: runtime error: left shift of 127 by 63 places cannot be represented in type 'long int' and an undefined negation: runtime error: negation of -9223372036854775808 cannot be represented in type 'long int'; cast to an unsigned type to negate this value to itself Both of these problems are readily avoided by havinng read_signed_leb128 work in an unsigned type, and then casting to the signed type at the return. ChangeLog 2018-08-27 Tom Tromey * dwarf2read.c (read_signed_leb128): Work in ULONGEST. --- gdb/ChangeLog | 4 ++++ gdb/dwarf2read.c | 6 +++--- 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index 86ef1c4040b..e61d6e04cb4 100644 --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -19600,7 +19600,7 @@ static LONGEST read_signed_leb128 (bfd *abfd, const gdb_byte *buf, unsigned int *bytes_read_ptr) { - LONGEST result; + ULONGEST result; int shift, num_read; unsigned char byte; @@ -19612,7 +19612,7 @@ read_signed_leb128 (bfd *abfd, const gdb_byte *buf, byte = bfd_get_8 (abfd, buf); buf++; num_read++; - result |= ((LONGEST) (byte & 127) << shift); + result |= ((ULONGEST) (byte & 127) << shift); shift += 7; if ((byte & 128) == 0) { @@ -19620,7 +19620,7 @@ read_signed_leb128 (bfd *abfd, const gdb_byte *buf, } } if ((shift < 8 * sizeof (result)) && (byte & 0x40)) - result |= -(((LONGEST) 1) << shift); + result |= -(((ULONGEST) 1) << shift); *bytes_read_ptr = num_read; return result; } -- 2.13.6