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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id 19-20020a621513000000b0056c0b98617esm3435797pfv.0.2022.11.18.09.06.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Nov 2022 09:06:31 -0800 (PST) Date: Fri, 18 Nov 2022 09:06:30 -0800 From: Kees Cook To: Vlastimil Babka Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH v2 2/2] slab: Remove special-casing of const 0 size allocations Message-ID: <202211180906.3030FDDB4@keescook> References: <20221118034713.gonna.754-kees@kernel.org> <20221118035200.1269184-2-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1668791192; a=rsa-sha256; cv=none; b=D49pr5FQe3e7t9KrY7DpP57abxfNYar1rpJbhO/oGHZzQoP1Mg+6RCzFukXy0P0G6SLLsx 7t2mKxGtWwKnzATU7crru0EcwhNZ2CC7yXPjIXRBSwnETCOD3tp7trOGRLj7zFdu8Eub8s 3VxZhsPz/yk74Ah3SxP5rC0Xwik/8P4= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=EF20HVvg; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf09.hostedemail.com: domain of keescook@chromium.org designates 209.85.215.175 as permitted sender) smtp.mailfrom=keescook@chromium.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1668791192; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=AGuGWp5XCDdHJkP/ZVzcY0JNFnAf0r/m3zS2HVfgluM=; b=Qep7Xk0YEb+ivNhLWCEF7U5Ob6rhLopD/YkyKYTmAETHrPkbGmwAVzzLyDyrZrKs+6bbFJ MP0fgVDK5sHokLkflPsUxo5NRCOiW6tZ1flgfPD5tNKpYnnLAWz1gDSROS1M+H3yrmM+NS GyLPJpMWeY//D9/HMQBZ7+BaPUDuG5I= X-Stat-Signature: atsum7qbfe5azsded6dpyep6hheck9jk X-Rspamd-Queue-Id: B2B3B140009 Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=EF20HVvg; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf09.hostedemail.com: domain of keescook@chromium.org designates 209.85.215.175 as permitted sender) smtp.mailfrom=keescook@chromium.org X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1668791192-37992 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Nov 18, 2022 at 12:34:01PM +0100, Vlastimil Babka wrote: > On 11/18/22 04:51, Kees Cook wrote: > > Passing a constant-0 size allocation into kmalloc() or kmalloc_node() > > does not need to be a fast-path operation, so the static return value > > can be removed entirely. This is in preparation for making sure that > > all paths through the inlines result in a full extern function call, > > So with the kmalloc_trace() already solved, we could now say it's not "in > preparation", but simply "makes sure", right? I can correct that while > picking this patch. Yeah, good point. I missed this when updating the commit logs. Thanks! -- Kees Cook