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 17B2BC001E0 for ; Sat, 21 Oct 2023 23:36:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229472AbjJUXg0 (ORCPT ); Sat, 21 Oct 2023 19:36:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52304 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229588AbjJUXgZ (ORCPT ); Sat, 21 Oct 2023 19:36:25 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 46DBAD76 for ; Sat, 21 Oct 2023 16:36:23 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ACE04C433C8; Sat, 21 Oct 2023 23:36:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697931382; bh=ePJsVbVghIPpOSlBWXWL3Zpf8CxGc78DT241F9Znn6s=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=Jes7izl8GIZDoZdhjcdKpFSDBNTYlqrZtRgp1KMFoTgz6Vv5Eg9lJrtxsgw+/Pd8k SCgmHgcw5X+ZY5Lx5o7GwzjY39xpPA+U3sDOGJZE+Ru6soJLTDHo/r5UVmYfmfz3NY ozD9uqdLam9a7jDUeLpi/XC3H8yV5WI3neuN/wWGYO3a+vVCAbxQBWKaA/8nURCTEk DAsVdxCchnhMtzBMEfwZx9HhMmYqcViHBYsFgLuv3pd3+AtEB03wR2aFJzxfDf/nta l5OzRTx3Tbnbysuqf6f4KlwSbKHQe9x6RVGDEgb2SPMwwVJd+CJugFtP4qfX21VsSf uyB5ST6KcupdA== Date: Sat, 21 Oct 2023 16:36:19 -0700 From: Kees Cook To: andy.shevchenko@gmail.com, Jan Kara CC: Andy Shevchenko , Baokun Li , Josh Poimboeuf , Nathan Chancellor , Nick Desaulniers , Kees Cook , Ferry Toth , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Subject: Re: [GIT PULL] ext2, quota, and udf fixes for 6.6-rc1 User-Agent: K-9 Mail for Android In-Reply-To: References: Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On October 20, 2023 1:36:36 PM PDT, andy=2Eshevchenko@gmail=2Ecom wrote: >That said, if you or anyone has ideas how to debug futher, I'm all ears! I don't think this has been tried yet: When I've had these kind of hard-to-find glitches I've used manual built-b= inary bisection=2E Assuming you have a source tree that works when built wi= th Clang and not with GCC: - build the tree with Clang with, say, O=3Dbuild-clang - build the tree with GCC, O=3Dbuild-gcc - make a new tree for testing: cp -a build-clang build-test - pick a suspect =2Eo file (or files) to copy from build-gcc into build-te= st - perform a relink: "make O=3Dbuild-test" should DTRT since the copied-in = =2Eo files should be newer than the =2Ea and other targets - test for failure, repeat Once you've isolated it to (hopefully) a single =2Eo file, then comes the = byte-by-byte analysis or something similar=2E=2E=2E I hope that helps! These kinds of bugs are super frustrating=2E -Kees --=20 Kees Cook