From patchwork Tue Oct 2 04:44:14 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tom Tromey X-Patchwork-Id: 29611 Received: (qmail 119875 invoked by alias); 2 Oct 2018 04:44:32 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 119797 invoked by uid 89); 2 Oct 2018 04:44:27 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-25.4 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RCVD_IN_DNSWL_NONE, SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=showed, ground X-HELO: gateway32.websitewelcome.com Received: from gateway32.websitewelcome.com (HELO gateway32.websitewelcome.com) (192.185.145.102) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 02 Oct 2018 04:44:25 +0000 Received: from cm16.websitewelcome.com (cm16.websitewelcome.com [100.42.49.19]) by gateway32.websitewelcome.com (Postfix) with ESMTP id B917C39F92 for ; Mon, 1 Oct 2018 23:44:23 -0500 (CDT) Received: from box5379.bluehost.com ([162.241.216.53]) by cmsmtp with SMTP id 7CXng6R8TaSey7CXngU2QE; Mon, 01 Oct 2018 23:44:23 -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=y4Y3OoSpIlRwbz7Ub8gsY4wAVNXwlpP+cr6xkE9Uan8=; b=Xd6qlMBX/gg24e7poCbZnLSnjW +i4du8joZnkzpabjtKJHvD0jIthiJG0R4+49FT+awqDUgx1bPf2P9tqozyI6T87ihRs4x8AxZAGpW OfoGWrReX96pGss4bJRYd0tzz; Received: from 97-122-190-66.hlrn.qwest.net ([97.122.190.66]:32984 helo=bapiya.Home) by box5379.bluehost.com with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91) (envelope-from ) id 1g7CXn-003mHT-Gg; Mon, 01 Oct 2018 23:44:23 -0500 From: Tom Tromey To: gdb-patches@sourceware.org Cc: Tom Tromey Subject: [PATCH v2 04/10] Avoid undefined behavior in extract_integer Date: Mon, 1 Oct 2018 22:44:14 -0600 Message-Id: <20181002044420.17628-5-tom@tromey.com> In-Reply-To: <20181002044420.17628-1-tom@tromey.com> References: <20181002044420.17628-1-tom@tromey.com> -fsanitize=undefined showed that extract_integer could left-shift a negative value, which is undefined. This patch fixes the problem by doing all the work in an unsigned type. This relies on implementation-defined behavior, but I tend to think we are on safe ground there. (Also, if need be, violations of this could probably be detected, either by configure or by a static_assert.) gdb/ChangeLog 2018-10-01 Tom Tromey * findvar.c (extract_integer): Do work in an unsigned type. --- gdb/ChangeLog | 4 ++++ gdb/findvar.c | 2 +- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/gdb/findvar.c b/gdb/findvar.c index 9256833ab6..be6c9d6f60 100644 --- a/gdb/findvar.c +++ b/gdb/findvar.c @@ -50,7 +50,7 @@ template T extract_integer (const gdb_byte *addr, int len, enum bfd_endian byte_order) { - T retval = 0; + typename std::make_unsigned::type retval = 0; const unsigned char *p; const unsigned char *startaddr = addr; const unsigned char *endaddr = startaddr + len;