From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B783F606A31A for ; Tue, 27 Oct 2026 09:41:13 +0000 (UTC) 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 Received: by kanga.kvack.org (Postfix) id D4D5B6B0669; Tue, 27 Oct 2026 05:41:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D25DB6B066B; Tue, 27 Oct 2026 05:41:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BEDA76B066C; Tue, 27 Oct 2026 05:41:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id A2A626B0669 for ; Tue, 27 Oct 2026 05:41:07 -0400 (EDT) Received: from smtpin14.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 3B86AC095B for ; Tue, 27 Oct 2026 09:41:07 +0000 (UTC) X-FDA: 85367912574.14.D4BCA40 Received: from mta0.migadu.com (out-14.mta0.migadu.com [91.218.175.14]) by imf15.hostedemail.com (Postfix) with ESMTP id 04B07A000B for ; Tue, 27 Oct 2026 09:41:04 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Wy8rVp9D; spf=pass (imf15.hostedemail.com: domain of muchun.song@linux.dev designates 91.218.175.14 as permitted sender) smtp.mailfrom=muchun.song@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793094065; b=taW2JwquCSss/+VcJzMqhcK5LP/LY0x0jAT/NtjI3A5Ocq5/SbQOHykoGWroNUm4jWLxP8 ZBpCZ4vw1hBjHYgc5Ujx7CW40x8tL1tXV62UOiJpOY09L3zLxKOIqT5nxA/Rgj5dWoo4G+ M+gDZYCA2pode3PkW6AJ1lNIX4ZsEFE= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Wy8rVp9D; spf=pass (imf15.hostedemail.com: domain of muchun.song@linux.dev designates 91.218.175.14 as permitted sender) smtp.mailfrom=muchun.song@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793094065; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=SFKyeuO1JPOzpTH1nQSbh9oibxPGA9YOhGPCshroXxs=; b=qorUqZ2nX895H0DJLhOGWDj01iqumb0Dn83U+KfLXEYf1S+oqlNxIifedDeWv9UOSFbzEM t87hUuEd/18uXOevRpvILGrznNxjU2ogBYUGTJNYzUKycIPy9/fBvG1F4aenIW7Ct9DM2M X8pUMrEOZd0UBEkFz2PfXnLVSlEtknc= X-Envelope-To: linux-mm@kvack.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-mm@kvack.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-Stat-Signature: 5ko8jiu7sdwrper3gdbsjgfi77wiatyi X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 04B07A000B X-Rspam-User: X-HE-Tag: 1793094064-850104 X-HE-Meta: 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 NmBcbIn0 5U7YN6jaxyadYiXYvbK9NHIosbiaKvaGLWwQZrD9f56M5MTRoDt6tX9j//xhMNarQsEdCWx1IVHXJUY2A5ZXgqqAiMWCzMtaDgfpuJHZaBEn0081KZkblWYbHQcAIgYSBeeYZrIetovHz5hyFnKKY7U3PAK+h7WgcNxzoHLMcPsAIWx0h3TyfErtVQr2rQijDx2Yw6Ge/QEBB5J52RySY+pOSJii4Z2eA+WrLXnYSeFybmYKVfpwWsABNhhg4amGqNPuuNtS6lBvNC5K1vb6srQaYf0hSNMiIJycJYPQjRSnt7HLhzcV7+57oVRw6DwhMG8J+NQFd1IEi1ySjokNNhmyxOSiuamedaSb+pHO0b43ERy5sikIhfp9fo2PHycm3aurZR9YpLCfsQK0dG8y/Dzm1O/9TzJPOL4K9c3IIoNL7iUKJfr8lEUGhnDVi31PilnCk Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: 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.