From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3032F606A31A for ; Tue, 27 Oct 2026 09:41:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=xzZT5Gnq; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=Wy8rVp9D DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:To:References:Message-Id: Content-Transfer-Encoding:Cc:Date:In-Reply-To:From:Subject:Mime-Version: Content-Type:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; bh=SFKyeuO1JPOzpTH1nQSbh9oibxPGA9YOhGPCshroXxs=; b=xzZT5GnqZwGFl2 Lc1GRg5m+NWFlkfpdAZT1K+nyaBZQq0RYX5SUbNRJGKxPlrlVUna+di3TgDNpdTriRthawzDt6cj/ AQP32sjv85g03xCTAHQh5MF3m1E/NP0MvrwjQ5TCo4wurVH3u2QCHP1AoFqULmf0fepUUg/ZbDs6d 45BaHCY3n3RcLOo5MzRxwl9cvxOVvvIYuE9jNDftYT67AdBVBb4GlkVIm+2vMMQLxg6gkOUCc7Jx+ 4DliKtcXJMv1vu3pJZOyVa79gQ2xEza8pmGhyuanhRIcpdHZWsQvNH0SE2XgNc2fn4P81EG7nd9wf 1oT6rPdV5tr6SQhEbEwA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xLdg5-00000004BtP-35UQ; Tue, 27 Oct 2026 09:41:09 +0000 Received: from out-127.mta1.migadu.com ([95.215.58.127] helo=mta1.migadu.com) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xLdg2-00000004BrU-2JNn for kexec@lists.infradead.org; Tue, 27 Oct 2026 09:41:08 +0000 X-Envelope-To: kexec@lists.infradead.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: kexec@lists.infradead.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-Archived-By: 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) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261027_024106_735397_F9C9FB4A X-CRM114-Status: UNSURE ( 9.57 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -2.1 (--) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-11.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 > 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.