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(p200300d82f1bb8006fdb1af24fbd1fdf.dip0.t-ipconnect.de. [2003:d8:2f1b:b800:6fdb:1af2:4fbd:1fdf]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-450d7f1afebsm199548075e9.0.2025.06.04.06.19.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Jun 2025 06:19:36 -0700 (PDT) Message-ID: <5de3da6b-7c5f-4d40-b3a7-f6a0f5cbc6da@redhat.com> Date: Wed, 4 Jun 2025 15:19:34 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] userfaultfd: correctly prevent registering VM_DROPPABLE regions To: Tal Zussman , Andrew Morton , Peter Xu , "Jason A. Donenfeld" , Alexander Viro , Christian Brauner , Jan Kara , Pavel Emelyanov , Andrea Arcangeli Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <20250603-uffd-fixes-v1-0-9c638c73f047@columbia.edu> <20250603-uffd-fixes-v1-1-9c638c73f047@columbia.edu> 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: <20250603-uffd-fixes-v1-1-9c638c73f047@columbia.edu> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 1jLJiDDQmjgXI4gWFNoweI-C7vRxaJYzah-uzleyJ6I_1749043177 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: rspam08 X-Rspamd-Queue-Id: E6B16A0016 X-Stat-Signature: egpuyojmzr6apu49w7q4gihy8wc1jbbq X-Rspam-User: X-HE-Tag: 1749043181-640605 X-HE-Meta: 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 fb2wlIAl GR73fvX5DhmCYblkT+efAafQUA73xZl8NY/DuRZsCtUPogAzo5SwmJdPrqbXlCpiF5dt0aRS0Z8hgZOihhb1QXG/t3CmMFKSnEPPbwz55nq4kMrLca3J5DVIlT6ixWEXJagGhIaMudc3zUG2uW7qUouxG8rqEmZNY23SVaykjXqZnpo/9YfuqQdGtOniONxMZWjENK3pq5yVB4NIhivBaMUA7qw9fRC3KCyZ39l6NZ9nqgGXpffv4RhoIaJJCt3Z5nN0UC5n2hpP6rvRHr1qhZ4d/Ug+ez1ezuQTQ458OEZuD+FmntlW2qybSyhJHTe7YMuutR82Sk88Puw0yXBNQ3GuukhvM74BLOpX0McyXVnbHXHGvYfxjcoWU21QOXlAz05V7OjZYJlAPdHOfAqlOIHP6GuAjzRPPwF2+EgWC9QBS4oB846CkzpXRyJy7SUX4l3kugjE/QyaD2tagD+NAas2c548ULyPN5m9XiA+f2lnQAasZhpcsh6mQvw== 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 04.06.25 00:14, Tal Zussman wrote: > vma_can_userfault() masks off non-userfaultfd VM flags from vm_flags. > The vm_flags & VM_DROPPABLE test will then always be false, incorrectly > allowing VM_DROPPABLE regions to be registered with userfaultfd. > > Additionally, vm_flags is not guaranteed to correspond to the actual > VMA's flags. Fix this test by checking the VMA's flags directly. > > Link: https://lore.kernel.org/linux-mm/5a875a3a-2243-4eab-856f-bc53ccfec3ea@redhat.com/ > Fixes: 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily freeable mappings") > Signed-off-by: Tal Zussman > --- > include/linux/userfaultfd_k.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h > index 75342022d144..f3b3d2c9dd5e 100644 > --- a/include/linux/userfaultfd_k.h > +++ b/include/linux/userfaultfd_k.h > @@ -218,7 +218,7 @@ static inline bool vma_can_userfault(struct vm_area_struct *vma, > { > vm_flags &= __VM_UFFD_FLAGS; > > - if (vm_flags & VM_DROPPABLE) > + if (vma->vm_flags & VM_DROPPABLE) > return false; > > if ((vm_flags & VM_UFFD_MINOR) && Nice catch! Acked-by: David Hildenbrand -- Cheers, David / dhildenb