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 EE4AAC77B73 for ; Thu, 27 Apr 2023 07:28:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242874AbjD0H2F (ORCPT ); Thu, 27 Apr 2023 03:28:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242971AbjD0H2B (ORCPT ); Thu, 27 Apr 2023 03:28:01 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22C094EFE; Thu, 27 Apr 2023 00:27:35 -0700 (PDT) Received: from kwepemm600003.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4Q6Rzm4bbtz18KXF; Thu, 27 Apr 2023 15:23:32 +0800 (CST) Received: from [10.67.111.205] (10.67.111.205) by kwepemm600003.china.huawei.com (7.193.23.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Thu, 27 Apr 2023 15:27:25 +0800 Subject: Re: [PATCH] perf symbols: Fix return incorrect build_id size in elf_read_build_id() To: Adrian Hunter , , , , , , , , , , , , References: <20230427012841.231729-1-yangjihong1@huawei.com> From: Yang Jihong Message-ID: Date: Thu, 27 Apr 2023 15:27:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.111.205] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemm600003.china.huawei.com (7.193.23.202) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org Hello, On 2023/4/27 14:02, Adrian Hunter wrote: > On 27/04/23 04:28, Yang Jihong wrote: >> In elf_read_build_id(), if gnu build_id is found, should return the size of >> the actually copied data. If descsz is greater thanBuild_ID_SIZE, >> write_buildid data access may occur. >> >> Fixes: be96ea8ffa78 ("perf symbols: Fix issue with binaries using 16-bytes buildids (v2)") >> Reported-by: Will Ochowicz >> Link: https://lore.kernel.org/lkml/CWLP265MB49702F7BA3D6D8F13E4B1A719C649@CWLP265MB4970.GBRP265.PROD.OUTLOOK.COM/T/ >> Tested-by: Will Ochowicz >> Signed-off-by: Yang Jihong > > As an aside, note that the build ID on the ELF file triggering the bug was > 62363266373430613439613534633666326432323334653665623530396566343938656130663039 > which is 80 ASCII characters, which would have been a 20 byte binary number i.e. > > $ echo -en "0000: 62363266373430613439613534633666\n0010: 32643232333465366562353039656634\n0020: 3938656130663039" | xxd -r | od -c -A d > 0000000 b 6 2 f 7 4 0 a 4 9 a 5 4 c 6 f > 0000016 2 d 2 2 3 4 e 6 e b 5 0 9 e f 4 > 0000032 9 8 e a 0 f 0 9 > 0000040 > > So perhaps a mistake in the creation of the build ID on that ELF file. > Yes, it may be an error, or it may be that the build-id was specified when the elf file was created. I tried ld can specify a build-id larger than 160-bit hexadecimal digits: $ ld -o test test.o --build-id=0x62363266373430613439613534633666326432323334653665623530396566343938656130663039 $ readelf -n test Displaying notes found in: .note.gnu.build-id Owner Data size Description GNU 0x00000028 NT_GNU_BUILD_ID (unique build ID bitstring) Build ID: 62363266373430613439613534633666326432323334653665623530396566343938656130663039 All in all, it feels like a rare scene :) > In any case, for the fix: > > Acked-by: Adrian Hunter > Thanks for the acked-by. Thanks, Yang