From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 20825537E5 for ; Fri, 12 Jan 2024 08:57:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="P3VLK2j1" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1705049837; 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=vW+ol7ud7h2MuKyZ+oGhxDOCyS1XZwRHB+bOAM3iCFI=; b=P3VLK2j11ucm7KcubtGtoRbw6DAk76QGQwjPJ+LsWBllkY+v4K/V8rDi0A+FCQc9NKbboZ ka8hTQzn3VHSxESk6O5FGCDmE5PpHb/gdVo/qSaNm8L1RnoCZbufFeIDW24wYPUDqoDeza nSAhrwRVlwhNMA0rtjO2EkhCLmSsgBs= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-686-6I4He00BMzSWhxmVjdnftg-1; Fri, 12 Jan 2024 03:57:15 -0500 X-MC-Unique: 6I4He00BMzSWhxmVjdnftg-1 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-40e41740b6eso53690495e9.3 for ; Fri, 12 Jan 2024 00:57:15 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705049834; x=1705654634; h=content-transfer-encoding:in-reply-to:organization:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=vW+ol7ud7h2MuKyZ+oGhxDOCyS1XZwRHB+bOAM3iCFI=; b=R4F/j1m8h9QFsJKk8OGCMM9iR7o7W+rg4ACm8CfJAh3xh0emiDfW6TuJdCSHMxJSyB qYKnDwaR+1QgMYVLMIlSodVmcN/PY+yPqMDnu+9ujUUKRNpzZygtyqNsPA++pb7vrwah R6Fz84GlBFRs0m/nMHAfaj35+IfNh/IzgChx7eb+LJIkMVFRQg7Cfs+XMqDnZYohCPVN sM5ijUdzXnUyQVXaYHkh5oXNpCSIw6SwLyiKAqM90JpQXiYg9y7bKhxlopQOjWrz03uj xwTtwFbI0DrbZ3EZk7tc2Pp1Gb7BNoHIqmj/IpbUU0Of4jBeQMHFJQkNKdwlaHoeXgdp xGYA== X-Gm-Message-State: AOJu0YwwKPyO34rEJjoD70LKruPjZBfq2nIeW0PYjS5W4KHIhCK6JSNC +LstD7Pt51A04OBUEgFoCsvyekIMDAdCD/oTrX0AZvI/WV6dIp/B+hNrD6RCSA7NVaO4qgE4CI3 8jPNpTHMZf5DcYC8WHBOCMTYO1S8nNWrN X-Received: by 2002:a05:600c:a44:b0:40e:5381:a3f4 with SMTP id c4-20020a05600c0a4400b0040e5381a3f4mr542348wmq.132.1705049834479; Fri, 12 Jan 2024 00:57:14 -0800 (PST) X-Google-Smtp-Source: AGHT+IEhoDkKX8I8gR/mGochqiZZrxkHpZlM0KzkKbRYLswMrqn5HM0RW8oybzkuEb4sCSClxaKzdg== X-Received: by 2002:a05:600c:a44:b0:40e:5381:a3f4 with SMTP id c4-20020a05600c0a4400b0040e5381a3f4mr542338wmq.132.1705049834079; Fri, 12 Jan 2024 00:57:14 -0800 (PST) Received: from ?IPV6:2003:cb:c705:5200:12dd:5a7f:d73:45df? (p200300cbc705520012dd5a7f0d7345df.dip0.t-ipconnect.de. [2003:cb:c705:5200:12dd:5a7f:d73:45df]) by smtp.gmail.com with ESMTPSA id r7-20020a05600c458700b0040e483aa5d1sm8836316wmo.24.2024.01.12.00.57.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 12 Jan 2024 00:57:13 -0800 (PST) Message-ID: <511e07da-9b34-4707-8f5a-f1e534c4445a@redhat.com> Date: Fri, 12 Jan 2024 09:57:12 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/1] userfaultfd: avoid huge_zero_page in UFFDIO_MOVE To: Suren Baghdasaryan , akpm@linux-foundation.org Cc: sfr@canb.auug.org.au, peterx@redhat.com, aarcange@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzbot+705209281e36404998f6@syzkaller.appspotmail.com References: <20240112013935.1474648-1-surenb@google.com> Content-Language: en-US From: David Hildenbrand 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: <20240112013935.1474648-1-surenb@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12.01.24 02:39, Suren Baghdasaryan wrote: > While testing UFFDIO_MOVE ioctl, syzbot triggered VM_BUG_ON_PAGE caused > by a call to PageAnonExclusive() with a huge_zero_page as a parameter. > UFFDIO_MOVE does not yet handle zeropages and returns EBUSY when one is > encountered. Add an early huge_zero_page check in the PMD move path > to avoid this situation. > > Reported-by: syzbot+705209281e36404998f6@syzkaller.appspotmail.com > Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI") > Signed-off-by: Suren Baghdasaryan > --- > Applies cleanly over linux-next, mm-stable and mm-unstable branches > > mm/userfaultfd.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index 216ab4c8621f..20e3b0d9cf7e 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -1393,6 +1393,12 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, struct mm_struct *mm, > err = -ENOENT; > break; > } > + /* Avoid moving zeropages for now */ > + if (is_huge_zero_pmd(*src_pmd)) { > + spin_unlock(ptl); > + err = -EBUSY; > + break; > + } As an alternative (and more future proof?) just reject anything that is not an anon folio as well? Anyhow, this should handle the issue at hand. Acked-by: David Hildenbrand -- Cheers, David / dhildenb