From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47A19C3600C for ; Tue, 8 Apr 2025 10:00:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9AD8F6B0008; Tue, 8 Apr 2025 06:00:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 95EDF6B000A; Tue, 8 Apr 2025 06:00:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7D6086B000C; Tue, 8 Apr 2025 06:00:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 5D2B96B0008 for ; Tue, 8 Apr 2025 06:00:32 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 380E81409B3 for ; Tue, 8 Apr 2025 10:00:33 +0000 (UTC) X-FDA: 83310431946.19.3D35BB5 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf18.hostedemail.com (Postfix) with ESMTP id ACE921C000D for ; Tue, 8 Apr 2025 10:00:30 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=f9wLpJAN; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf18.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1744106430; 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=wGU6be8Iks6z0gUVjQ3GgVLTq8eDFjYIyM80DG5Gz4c=; b=EGCUAPouft2v4srC1jWbyPDOhY1MA0YC1jHVkpnjuNC6UOfgIkwxu4giTLj0WTT9G2GRPx MuodDgHKlGXSqQzhY80qJ77RkzzNcDlH/7/I2/JG121dcfpy2Q2N1nAuIH43BlL32xUUgi KnqPkdAdeBArGfUXHO0HA6TcH2R4vyA= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=f9wLpJAN; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf18.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1744106430; a=rsa-sha256; cv=none; b=1jg35TY/27GFKEewV8mpC0ayoiyctq9rPG0AcwjdhuolrqIJnl1xSGHyldg6/2/7aj4g/3 USQEhBMPdkWzYAiYFhcffAOQ+Gc5rEEAdEhMAVLPmCjNqvKjwQrDME8/PbjF8oFE5RWuO9 I3NSy2Yb485/r0dQEA0zgnyh8zXpKeQ= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744106430; h=from:from: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:autocrypt:autocrypt; bh=wGU6be8Iks6z0gUVjQ3GgVLTq8eDFjYIyM80DG5Gz4c=; b=f9wLpJANpxEd/3tFa8uaFF2o/XKUgAbRdsbP48tBnHKxSqa2rqTgUZWNk/hIFstj1jFq7l DP5CgbcI83hMtA2w1R/3Yt20kheMX/piF8TaVygRxl+QVdU1Ht0bgzte+Hl+vJDCshSLtW eZDwCFA+wqHqtvTtacDSJ5uj+JVLqVw= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-656-XuH7RAsUOSaY860HHRLJQw-1; Tue, 08 Apr 2025 06:00:29 -0400 X-MC-Unique: XuH7RAsUOSaY860HHRLJQw-1 X-Mimecast-MFC-AGG-ID: XuH7RAsUOSaY860HHRLJQw_1744106428 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-39c2da64df9so3553516f8f.0 for ; Tue, 08 Apr 2025 03:00:28 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1744106428; x=1744711228; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:references:cc:to:from:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=wGU6be8Iks6z0gUVjQ3GgVLTq8eDFjYIyM80DG5Gz4c=; b=vM9wdqXKzMN3tIWH8BLtBDE2QMtel4lmOfTGxFnDVyNek0W0rBUYSfugC2Wy0Qf+qM IQuZllLguukrMyRCfRgHPvgENZbfCm27Bu4flnrEi5SwZSvS2+kTD8Ua9fGlXJhP7p3g SCw+5vmoaVZF3qcE0zG+DqbXHDjlBv2JgcBAb35F8pVIn2FGbaXespPP8D1MhxKyp9hE M4yoJ7JNrnoEICgL4qCYRJ/kv/B6pcMNhl/OnGQItAoXu9UNOf+l5JRZEII5XS71N1pm +ws9L7VW3tzFlcCEjJJ/F4M0lJxB9l0Q2Dwlga+dOAbewz8tgVT6fgOWOegPNJ9kmfju Kplg== X-Forwarded-Encrypted: i=1; AJvYcCU6OV3ujIgU1H33lX18dsmJoo1KnfMz4PfsHBYIRHmqx8pwKlT4dPOAx39mWlLHW1lsi0Zlm1WLjA==@kvack.org X-Gm-Message-State: AOJu0Yx8pCrpGrNlsV5Z8ifgEasMoY5w9cmk0pJH+UO8USuhtK8FWV6z eyU4XW55lisnE9PNFwJd/PlMDQCGZLRb137DNe5lSPCTu44/+c4cawlUKnYD7oPax+/F3t0PAAW LNIZWDhK+hsmMF0csXbG98UGVf7uUK43dU/rHAAZOblBa2x5X X-Gm-Gg: ASbGncvDysrlA5m7foYc1JO4vnEiPW7VXvfYlN/16T1Ddj9bz94otYOplYbtkogSoUb WROXKVRsa3KSJC6qeX1muWslG0Oyr3jTigFqnM/kQIBzXYeaPRihiA2O46wkUsNHbDxl//1mPnb qGu8EPlbtuQrdYBJg/LkO1MgnGVm6Z4IPw2dsg65iJv7mjLPVelGlFukRfuVGTejVTAKT7HFnhJ JLnDEyJUCdAcAVjsq15N5cDY+umBTyp4yxQskoxM2aasuqcMbx7FjGVhnFDQxGP4IRTv6o05I75 FWC+cRncskqEceUeQwsHgp7ghO5+YMbkgRwslO0FRoUSrzF5l2fLcSkV6w/Bo86eBeyYhLY97+s jT2PdFsJq6ifxkfhxQU2RcR9+eoTwDTDtzYj+XXs0 X-Received: by 2002:a05:6000:420a:b0:391:487f:27e7 with SMTP id ffacd0b85a97d-39cba98bb36mr12802647f8f.55.1744106427775; Tue, 08 Apr 2025 03:00:27 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGMLyxSrpbvzEc6BfSO+YZMc/HKz7loupC7FOQVU7niLonQu4qcqbEjcVzu/K2oUBWR45IJuw== X-Received: by 2002:a05:6000:420a:b0:391:487f:27e7 with SMTP id ffacd0b85a97d-39cba98bb36mr12802626f8f.55.1744106427450; Tue, 08 Apr 2025 03:00:27 -0700 (PDT) Received: from ?IPV6:2003:cb:c707:4f00:a44a:5ad6:765a:635? (p200300cbc7074f00a44a5ad6765a0635.dip0.t-ipconnect.de. [2003:cb:c707:4f00:a44a:5ad6:765a:635]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39c301a6ae5sm14620018f8f.32.2025.04.08.03.00.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Apr 2025 03:00:27 -0700 (PDT) Message-ID: Date: Tue, 8 Apr 2025 12:00:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/3] mm/gup: fix wrongly calculated returned value in fault_in_safe_writeable() From: David Hildenbrand To: Baoquan He , linux-mm@kvack.org Cc: akpm@linux-foundation.org, osalvador@suse.de, mingo@kernel.org, yanjun.zhu@linux.dev, linux-kernel@vger.kernel.org References: <20250407030306.411977-1-bhe@redhat.com> <20250407030306.411977-2-bhe@redhat.com> Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: FcTos8cYq8IXfgBYtAkkWCaNKwFB6rG0iqdiglZE7AE_1744106428 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: ACE921C000D X-Stat-Signature: wbjkwmfh4575n7pputs44daexe5qx9st X-Rspam-User: X-HE-Tag: 1744106430-59433 X-HE-Meta: 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 ugTxSEqI 3jnT5rhLjfCxx5T+Xvdqe+nAyIAhKROzIJo7eljaYauHsQX0aj6EI8AgNomdyvTtrINagtQUn0UPgFwFvCyP1d0sKi1ozDXTeIL0hL28bdU3U88GynYbK82WIBD1vC3k0E4C6q/8uKNudVAU9h5JJhnU/MUyTVkFpb9oJFhJF6beEPBuucE5tvZr2QsjgY1XT4H+ebmD54U6ioW1Lf5xxJ53MSEeesETZ5peEFOQzRk6F80KWjuMPr2Nm6l7OWsKwe3r96wUW5QVjyA7Gi7cog9LGoCAd2+SofOpaRD+TMtrB11z04aBdfldJeVSgvKUqR7q981ltE8kKF94uFz1BPJljq+lXfzO/X7rXGUeJyHeixcD/A9qKB/rae372Il0ATnEobD+yeukIRxUeJnNH1icuLH092edP7r+A+Ak/77oXRukdFypU1RRz50/0JAi4EJFQ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 08.04.25 11:52, David Hildenbrand wrote: > On 07.04.25 05:03, Baoquan He wrote: >> Not like fault_in_readable() or fault_in_writeable(), in >> fault_in_safe_writeable() local variable 'start' is increased page >> by page to loop till the whole address range is handled. However, >> it mistakenly calcalates the size of handled range with 'uaddr - start'. >> >> Here fix the code bug in fault_in_safe_writeable(), and also adjusting >> the codes in fault_in_readable() and fault_in_writeable() to use local >> variable 'start' to loop so that codes in these three functions are >> consistent. >> > > I probably phrased it poorly in my other reply: the confusing part (to > me) is adjusting "start". Maybe we should have unsigned long start,end,cur; > > Maybe we should really split the "fix" from the cleanups, and tag the > fix with a Fixes:. > > I was wondering if these functions could be simplified a bit. But the > overflow handling is a bit nasty. FWIW, maybe the following could work and clarify things. Just a thought. diff --git a/mm/gup.c b/mm/gup.c index 92351e2fa876b..7a3f78a209f8b 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2223,30 +2223,23 @@ EXPORT_SYMBOL(fault_in_safe_writeable); */ size_t fault_in_readable(const char __user *uaddr, size_t size) { - const char __user *start = uaddr, *end; + const unsigned long start = (unsigned long)uaddr; + const unsigned long end = start + size; + unsigned long cur; volatile char c; if (unlikely(size == 0)) return 0; if (!user_read_access_begin(uaddr, size)) return size; - if (!PAGE_ALIGNED(uaddr)) { - unsafe_get_user(c, uaddr, out); - uaddr = (const char __user *)PAGE_ALIGN((unsigned long)uaddr); - } - end = (const char __user *)PAGE_ALIGN((unsigned long)start + size); - if (unlikely(end < start)) - end = NULL; - while (uaddr != end) { - unsafe_get_user(c, uaddr, out); - uaddr += PAGE_SIZE; - } - -out: + /* Stop once we overflow to 0. */ + for (cur = start; cur && cur < end; cur = PAGE_ALIGN_DOWN(cur + PAGE_SIZE)) + unsafe_get_user(c, (const char __user *)cur, out); user_read_access_end(); (void)c; - if (size > uaddr - start) - return size - (uaddr - start); +out: + if (size > cur - start) + return size - (cur - start); return 0; } EXPORT_SYMBOL(fault_in_readable); -- Cheers, David / dhildenb