From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gnu.wildebeest.org (gnu.wildebeest.org [45.83.234.184]) by sourceware.org (Postfix) with ESMTPS id 247A9385B522 for ; Tue, 14 Nov 2023 12:57:29 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 247A9385B522 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=klomp.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=klomp.org ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 247A9385B522 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=45.83.234.184 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1699966650; cv=none; b=jAX6pVFnn7GL3lh2aqx65vcSihLvBUqGPwrjGRBD7x9NXGckISV2SWOuIJGoyqrBtKyLZUf9H7ei9tea6SoDxCF3ZUOc9cUI8RYukxgtu9xuR/6a5CfJwf/ZAC8IGUFbiYGHnes3miqMkngz4q/qUprrXpJog99j51Xvrw714Kg= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1699966650; c=relaxed/simple; bh=NVv/NPWA4f1wjggAs5LHjFkMoKN7o7cx5yGJCRjqn9g=; h=Message-ID:Subject:From:To:Date:MIME-Version; b=uAS4ZntLYa1EeuMVbV4WQTpdalOT6snvYKOEs2HuyNqLXnkxTv0MVDThhnATfGgSUa2njvIFBJVWybpr2uGqnnl6VFw1ruN41DC85Z5Am0SQnG8iOS2rY6IBJmHwg/YrJLM0FNNZMIRk6Tcaldyu7fIGqi8v/YohjS0yqx3aifY= ARC-Authentication-Results: i=1; server2.sourceware.org Received: from r6.localdomain (82-217-174-174.cable.dynamic.v4.ziggo.nl [82.217.174.174]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by gnu.wildebeest.org (Postfix) with ESMTPSA id 27F83302FDDB; Tue, 14 Nov 2023 13:57:28 +0100 (CET) Received: by r6.localdomain (Postfix, from userid 1000) id D7A4E340234; Tue, 14 Nov 2023 13:57:27 +0100 (CET) Message-ID: Subject: Re: [PATCH] Fix computations with (potentially) NULL pointer From: Mark Wielaard To: Paul Pluzhnikov , elfutils-devel@sourceware.org Cc: nafi@google.com, maennich@google.com Date: Tue, 14 Nov 2023 13:57:27 +0100 In-Reply-To: <20231113225835.4083255-2-ppluzhnikov@google.com> References: <20231113225835.4083255-2-ppluzhnikov@google.com> Autocrypt: addr=mark@klomp.org; prefer-encrypt=mutual; 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 QifSU1tvZxQ== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.1 (3.50.1-1.fc39) MIME-Version: 1.0 X-Spam-Status: No, score=-3026.6 required=5.0 tests=BAYES_00,JMQ_SPF_NEUTRAL,KAM_DMARC_STATUS,RCVD_IN_BARRACUDACENTRAL,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Hi Paul, Hi Nafi, On Mon, 2023-11-13 at 22:58 +0000, Paul Pluzhnikov wrote: > When map_address is NULL, computing map_address+offset is technically > undefined behavior, and triggers Clang/LLVM warning when using > -fsanitize=3Dpointer-overflow. Urgh, I had no idea NULL + ... was technically undefined behavior. > Fix this by using uintptr_t to perform computations. I can see how this solves the the issue. It would be slightly nicer if we could just do the computation after checking map_address !=3D NULL (since ehdr is only used after such a check). That would require rearranging some of the if statements. Does that make the code too complicated? Also this only resolves the issue for the 64bit ELF case. Just above this code is basically the same code for 32bit ELF. That code also needs to be fixed. Thanks, Mark