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R . Silva" , Bill Wendling , Justin Stitt , Jann Horn , Przemek Kitszel , Marco Elver , Greg Kroah-Hartman , Sasha Levin , linux-mm@kvack.org, Randy Dunlap , Miguel Ojeda , Vegard Nossum , Harry Yoo , Nathan Chancellor , Peter Zijlstra , Nick Desaulniers , Jonathan Corbet , Jakub Kicinski , Yafang Shao , Tony Ambardar , Alexander Lobakin , Jan Hendrik Farr , Alexander Potapenko , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, linux-doc@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v5 2/4] slab: Introduce kmalloc_obj() and family Message-ID: References: <20251122014258.do.018-kees@kernel.org> <20251122014304.3417954-2-kees@kernel.org> <202511241119.C547DEF80@keescook> <202511241317.516BDE7B@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <202511241317.516BDE7B@keescook> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: E90AD40009 X-Stat-Signature: dquod1usimgqfidp48r59a4mxswmqrfg X-Rspam-User: X-HE-Tag: 1764020668-277648 X-HE-Meta: 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 P5L8bAII bkqV8nUDNNd8XhZd325WLFPxD/f1bqond7RMvuEkyIB8Be+EREmnGFSdA7WOV7VjoU1QQu1DiJAx5umMId8qsf+NbRdS5XcU8LdH143S2kGQqaJG3+b3OrsChWtkiBonilZTJLZCmAqhnTprsEwtBnBmxUK6P+BQc9OuwivL++1I6qYwbiyT9WkLjHV5Xhl2SNE2rqGyBBUnpjO06mfG2KAI//QafIaFkei0NEwtOGrPqwmkBT8l0OzUi8QPv6xCeBBMbcujN7R8hu1jQwvbAjizj2gQg6VVr0HYryHM6rtq/Jpc1e6q2jjss/YW07hhWB+elJLgS3C/QoELiWGnBnEuJSt3sTG/UGGXj7pw3tDr5GQrptBGV8TecW35qJU2D9fY+Tju+84fQ9nVDf7o47tbzPQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Nov 24, 2025 at 01:20:21PM -0800, Kees Cook wrote: > Yes, -Wconversion (W=3) is mind-blowingly noisy, unfortunately. This third one is interesting. include/linux/jump_label.h:126:44: error: conversion to ‘long unsigned int’ from ‘s32’ {aka ‘int’} may change the sign of the result [-Werror=sign-conversion] 126 | return (unsigned long)&entry->code + entry->code; static inline unsigned long jump_entry_code(const struct jump_entry *entry) { return (unsigned long)&entry->code + entry->code; } The warning is ... not the best phrased, but in terms of divining the programmer's intent, I genuinely don't know if this code is supposed to zero-extend or sign-extend the s32 to unsigned long. I know what it *does*, but I don't know if it was *supposed to do that*. So I wuold be in favour of enabling this warning ... if we have a small army of people on tap to get the kernel to build. There's 374 lines of errors to fix from the header files included by scripts/mod/devicetable-offsets.s alone.