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 0AFD4606A325 for ; Tue, 27 Oct 2026 09:35:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Z3V2ir1f Received: by kanga.kvack.org (Postfix) id AAB7F6B0657; Tue, 27 Oct 2026 05:35:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A836A6B0659; Tue, 27 Oct 2026 05:35:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 999026B065A; Tue, 27 Oct 2026 05:35:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 637336B0657 for ; Tue, 27 Oct 2026 05:35:18 -0400 (EDT) Received: from smtpin29.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 31D594098B for ; Tue, 27 Oct 2026 09:35:16 +0000 (UTC) X-FDA: 85367897832.29.717248F Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf02.hostedemail.com (Postfix) with ESMTP id A31A280005 for ; Tue, 27 Oct 2026 09:35:14 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Z3V2ir1f; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf02.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793093714; 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=GyDf/T3A99e/UK5Tx0KKev7xPaxEfXMruyrCYj6de1U=; b=IJ1J8aM2h67GvoEDeBY0b/5EuFgpwglFERqhJ6P5YiSzBWhoXhthMRZVie06pqOV4axH3J k1lRRhlxGuCqvd42FAAqf8SvXa0jHE6S6IX1SMr6Kn6npn0m9x6AO1BSsrSJcblcZYWs2K V95Eb3rqwsWy0NxLLZ/fKCxAMUMzKZc= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Z3V2ir1f; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf02.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793093714; b=2Q4/CG6piJ+UEu9+gWZVAeTs7H23FRVtbY1o0NNzJfFBA0tDG83dfKv2QOcIiYcPN/yu0B mqNKObX1lomF1euk8TeNxwLN8a2+y7VANe3sMxqvDo0Sedfl6MdEut9M31FQhFpkZvS35x PuOFZ+/sdFuTdQxfMPJeumsqPIYsoi4= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 2E4E460052; Tue, 27 Oct 2026 09:35:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4CD641F01825; Tue, 27 Oct 2026 09:35:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793093713; bh=GyDf/T3A99e/UK5Tx0KKev7xPaxEfXMruyrCYj6de1U=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Z3V2ir1fhLjLEOG38tPqPyKd7K/FHGfPC09OfR7eOlE/pdqk+8s3kVa1i4DQbH+Qx MZ32NLc7julvf25Egjxt2K1dVEewhL3Of9L8IHSEkMikSMuPsfkdtPqT3BAFRQIx4l I2aocqwSNzVOB8HXoD0iEYYGXcOv8ZXfRuVth/j1TS6G/Q38VWONKl+4C7n5MEPxNA MdDQY8Y20j6O/Wno2AqROjn/Br7ZnF59rm1EwFzdyTg2TjL0F8dx2lgZTIglHC5tyA DHYvTnMV0DHzDPWwpSElNE8EW4/oPBEyMA8Gm39jeV4/zgUOyB58UgoLt0XQBoz9Do 0CxG7SV58ggfg== Date: Tue, 27 Oct 2026 09:34:57 +0000 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , 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 , Muchun Song , 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, stable@vger.kernel.org Subject: Re: [PATCH 22/46] mm/gup: check for overflow when converting nr_pages to bytes in GUP-fast Message-ID: References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-22-6f74bec9a5bb@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261027-fixes_core-v1-22-6f74bec9a5bb@kernel.org> X-Rspamd-Queue-Id: A31A280005 X-Stat-Signature: tinyga3hdhu1stq613zfamcipatos9x5 X-Rspamd-Server: rspam04 X-Spam-Status: No, score=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793093714-728426 X-HE-Meta: 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 NyCCRgJn reDbqzMsJIk8JEuQdgW4TlKuYAuDdenIh9EDxxn8IkSH/79ImKhOQ5e4Nw+XV7hI0B2+YXvY8e/e5H2M0gtx+dr/ekBuaxHXX1qZNlBfLNWbul5Zj5kKDYOrDLpFymiBQUtBy42FpDDf3Ygx07/7CF8XcPPZkGhfu9ITbe997EDWKC2CIdd6c2MRfIVWw/R+R6dnq+pukBi3wswjJsd3hyuJ3g59nBPQAf5kL3B3PvwtAvv/CtSDMGs74DbYnBTAHHMA+vdPpqfdG+QPOmcTpuOWsHlaFSx+/OMQuo76EhZn2Jqh+JkUzysiY6TLJP2uqSS292JPbPOe5qQe3jcZJCxb3yeXt5u3j49zKGgshVeChAzWl/l3P9lnwJ6Ij9Fon9JNax5sgNpztcxE= 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 Tue, Oct 27, 2026 at 12:17:42AM +0100, David Hildenbrand (Arm) wrote: > The overflow check in gup_fast_fallback() only covers the addition to > start. The preceding nr_pages << PAGE_SHIFT can already have truncated > the length on 32bit. Insert rant about 32-bit kernels here :) > > Users such as RapidIO's rio_dma_transfer() can derive such page counts > from a 64-bit userspace length. > > Let's just check_shl_overflow() to reject any such overflow with > -EOVERFLOW early. > > Fixes: c28b1fc70390 ("mm/gup: reorganize internal_get_user_pages_fast()") > Cc: stable@vger.kernel.org > Signed-off-by: David Hildenbrand (Arm) Reviewed-by: Lorenzo Stoakes (ARM) > --- > mm/gup.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 9906965893431..48e1bfe5ab9a9 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -3214,8 +3214,8 @@ static int gup_fast_fallback(unsigned long start, unsigned long nr_pages, > might_lock_read(¤t->mm->mmap_lock); > > start = untagged_addr(start) & PAGE_MASK; > - len = nr_pages << PAGE_SHIFT; > - if (check_add_overflow(start, len, &end)) > + if (check_shl_overflow(nr_pages, PAGE_SHIFT, &len) || > + check_add_overflow(start, len, &end)) > return -EOVERFLOW; > if (end > TASK_SIZE_MAX) > return -EFAULT; > > -- > 2.43.0 > -- Cheers, Lorenzo