From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.outflux.net (smtp.outflux.net [198.145.64.163]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E3A4A339B37 for ; Sat, 31 Jan 2026 18:49:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.145.64.163 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769885342; cv=none; b=GTajG0iix1vfXbeXDmVPIumseJY/LJms9Nf4rAzxsdNFMpNxqokY4l65IDYWzcjzb8SXe4GIthuzxUHqpzrwlwtJzahvCORN2Sk4f4ZlrSsLGJSwF1li/HAVi3/8kqXvZXRclEuxuH1/xA8E2YbB/mIRTaN/vHFrd/PpK0FLmpw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769885342; c=relaxed/simple; bh=WtuIXy0BMT9x97HymW4yfJH3ViNO1Fkx7J0TCNwWx70=; h=Date:From:To:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=HTjpM4ejfNoD0hwfMwlz3nskj1c92GxLmoxbcxYLNMA4v7LF3veq90+yD9BX+RVaj2wJrouMgdYxRvEp95eQsKgjNwKUDRVpeJuCiYk8fchOqu8BjVyIpg61GwsbrSBzzzE/qvhNjWWZ+o5ffcGZXNqUrMvrRhb7fsIgweaGiPg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org; spf=none smtp.mailfrom=debian.org; arc=none smtp.client-ip=198.145.64.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=debian.org Received: from serenity.outflux.net (serenity.outflux.net [10.2.0.2]) by vinyl.outflux.net (8.15.2/8.15.2/Debian-10) with ESMTP id 60VIgZnI003091; Sat, 31 Jan 2026 10:42:36 -0800 Authentication-Results: vinyl.outflux.net; dkim=none; dkim-atps=neutral Date: Sat, 31 Jan 2026 10:42:35 -0800 From: Kees Cook To: Peter Zijlstra , mingo@kernel.org, oleg@redhat.com, linux-kernel@vger.kernel.org, debian-kernel@lists.debian.org, kees@kernel.org Subject: Re: [PATCH] seqlock: Allow UBSAN to fail optimizing Message-ID: References: <20260129110733.GA166857@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Debian X-MIMEDefang-Filter: outflux$Revision: 1.316 $ X-HELO: serenity.outflux.net Envelope-To: linux-kernel@vger.kernel.org Envelope-To: oleg@redhat.com Envelope-To: debian-kernel@lists.debian.org Envelope-To: mingo@kernel.org Envelope-To: kees@kernel.org Envelope-To: peterz@infradead.org X-Scanned-By: MIMEDefang 2.83 On Sat, Jan 31, 2026 at 10:39:42AM +0100, Salvatore Bonaccorso wrote: > Kees, Peter approached the Debian kernel list above to drop > CONFIG_UBSAN again, which, so I think we need to revert your > 6cfadabfe015 ("Enable UBSAN_BOUNDS and UBSAN_SHIFT"): > https://salsa.debian.org/kernel-team/linux/-/commit/6cfadabfe015fa0d659fc8e3efd495cbcae3e44e > > I have make a MR for our packaging for the change in > https://salsa.debian.org/kernel-team/linux/-/merge_requests/1804 I am strongly opposed -- this undoes years of security flaw mitigation work and leaves Debian (and only Debian!) exposed to trivial array index overflows. The bounds sanitizer is the corner stone of memory safety for C, and is not some "experimental" feature. GCC has a long history of trouble with inlining, so this is not something unique to enabling this feature. I replied similarly to the PR. This would be a major mistake to disable. -Kees -- Kees Cook @debian.org