From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.13 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793094065; b=pwBk4P61wu6v+uScqXX/RoI4kN7eSBIe23HyqJn2pENOmc1RBIXZgNPLMlFC/DYF/Oaw ss1/5azSNhO62rePE1/TwwiHEymM9C7lupUB7Toc9goVRh/iCzXo7Xed+s8ahliwZDjsS WASG//8xWR2eDcD3pPWtemil+rjghawnDynbwgjeJm9dVVHw8kvA3dJqbCqh9ZaifzedW XYkJwFm8/MNnxkchVtED2FIV9+nU/KaZRRYAm0B95HkaHOw9rJPIBPn5v95aza8rSEjfV 3/8S1aOt4SZo8c24ll3Z0nfX3qnfulA8WsJq0oXgRiih1HCBFfEZxd8yPUovKeyKd/Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793094065; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Content-Type:Mime-Version:Subject:From: In-Reply-To:Date:Cc:Content-Transfer-Encoding:Message-Id:References: To:X-Mailer; bh=SFKyeuO1JPOzpTH1nQSbh9oibxPGA9YOhGPCshroXxs=; b=Cw3NlnjVQx+RFXIoEYAATy7nndg/YUL0oULl4cMaIC2Nkpk7ahuywDsxaQq5h4D4o6jE /EtGU8ArJilO1/AU6F+J6U/v+YLg7CUZ9fImO/0PI+sJUX1R9s8eef100mnidOR5HhV6C 0/Y1S7ncknSD62fMxkDjOfVp1B7S13FF31VLlDxMaTbQGvqzInrBTyuNWtXF1ZCuh1/Cz DF672NJIjzldSyIHZZD0fTH/arXqRMmqs9I5twOKEIzA3v3fnc6mMk3CLUy58RmM2U49F qngaZofjO8J3Hh4yuMUBiLEOt+LcEar+6EgaDPTnmdtjmiqK13NRgiOsUhLVpcJLP/w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=Wy8rVp9D; arc=none smtp.remote-ip=91.218.175.13 Received: from mta0.migadu.com (out-13.mta0.migadu.com [91.218.175.13]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F018D606A33F for ; Tue, 27 Oct 2026 09:41:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org F018D606A33F Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=Wy8rVp9D X-Envelope-To: linux-cxl@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=SFKyeuO1JPOzpTH1nQSbh9oibxPGA9YOhGPCshroXxs=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793094062; v=1; x=1793698862; b=Wy8rVp9DDbUKlyVz5wuK1Feezur9xae+q/Z6Hz9yNW58v47WUH5wcaD9Hrg3xWbyvhu39BqI ExWkcwZHN1517KLsoJWC0uj/l5WpUULFpWzYP0SvVGopmxnWl4TptAwsG4qqUQ92vI72Mtsn8k9 0zb7+9ocVTbtmM6u1o472cEA= X-Envelope-To: linux-cxl@vger.kernel.org Received: by mta12.migadu.com with ESMTPS id caa1b482120fcdcd; Tue, 27 Oct 2026 09:41:01 +0000 X-Mizu-Trace-ID: caa1b482120fcdcd X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=us-ascii X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3901.100.1.1.12\)) Subject: Re: [PATCH 21/46] mm/gup: fix out-of-bounds write for nr_pages == 0 in GUP-fast From: Muchun Song In-Reply-To: <20261027-fixes_core-v1-21-6f74bec9a5bb@kernel.org> Date: Tue, 27 Oct 2026 17:40:31 +0800 Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, Chris Mason , stable@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <31275548-1D1D-46D7-A0FE-36D16C03384F@linux.dev> References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-21-6f74bec9a5bb@kernel.org> To: "David Hildenbrand (Arm)" X-Mailer: Apple Mail (2.3901.100.1.1.12) > On Oct 27, 2026, at 07:17, David Hildenbrand (Arm) = wrote: >=20 > From: Chris Mason >=20 > With nr_pages =3D=3D 0, GUP-fast still enters its page table walk and = can > write past the caller's page array. The old end <=3D start check = caught > empty ranges, but was replaced with an overflow check. >=20 > Users such as OrangeFS can pass a zero page count derived from a > userspace-supplied length. So let's return zero for nr_pages =3D=3D 0 = before > starting the walk, just like GUP-slow. >=20 > Fix generated by an LLM and sent by Chris Mason in private. >=20 > Fixes: c28b1fc70390 ("mm/gup: reorganize = internal_get_user_pages_fast()") > Cc: stable@vger.kernel.org > Signed-off-by: Chris Mason > [ david: simplify description ] > Signed-off-by: David Hildenbrand (Arm) Acked-by: Muchun Song Thanks.