From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794057485; b=AWtXtwibTi3VgeVqr2W6XLqr7kcic+dnaxhy7P/CfiiRz/Mhm/LwGD2S6/aixidx3HwH nJxqUApRUdXWraqTT/Um3ik/bhOghzu2oAsxARyNBy81kI5SfTlTncihzSpU7TOl2ZQGn SVw8xMVnVwKUNQ1YeP2uJRvOGzdrGl/PVT5nOMfO1rdGchyQgGoVY3/wju4pNKOWoBruq 60gUJjuJsxWwO3Jr/Lo5r1mYw0VZlK0rEn47VfyGTnubMOWleHiNFf/p1QIQrgq3KGAvy WZTPeyYNsQgVQAAe6MfOlVpy0hF9ClkVFs+Szpex6K6taXIhVhbVJ4uP68tumopXmkA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794057485; h=Received:DKIM-Signature:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:Content-Language:Autocrypt:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=WHIeRQXEN/cLq4RDZzIjHJg7538MWLG7Xtt4v6NPKig=; b=qhWeAFmxNXyikAXXU7s2g401Mj8QGDP7Z4Ak+uck5XAq00797CxMVl1lPMOROrEP9zLo yEclsz7zmj7hW7yXAgTKnrExr07E4r7VFYMlMYewAkeOAm/HNVxWlrTziEcDxRoCkbAop FclLnA8adOhHLag4nN7dB5cA+qkdscsXvwNeCk8gL+7sdb1XXMgLFIkbt8pEd/JkqfLyv yTe8e8NmQMYEu+prlpxB0Gu8BC4Mob+Eybxl+1hgwYkh514bYB79pgkOCCY/IPTxBn34e hZEYDVjXWQ0Me8IjMdU4rBWmx18nwOYbTd4zPNWtuCtjpn50BkShKWLb34+Q4Wgu39g== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=dmodx5Fs; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8CA29606A32C for ; Sat, 7 Nov 2026 13:18:05 +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=dmodx5Fs Received: by smtp.kernel.org (Postfix) with ESMTPSA id B3CFA1F0089F; Sat, 7 Nov 2026 13:18:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794057485; bh=WHIeRQXEN/cLq4RDZzIjHJg7538MWLG7Xtt4v6NPKig=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=dmodx5FsiwXCu5bCklY+ydYX0FIUmCxrsDzsFLtOh0GTw9MNSoUPtk3zPRKKbP5ep XUZASmIqNRpBJnKezD2+Z0fPtOiQpuw/SXRJ49RgSFG9MM6whfwgFHjUh2KL+PjmZE CpBEeILbLiHqCVPO7B961xZAm1TmrPHV3aFB41z9LbX3rKDvicyY3oiiltvZKfsnfY w7PMu9dtqIY2kQPyZ9OQQYKTiykkHTk+lJwJkniTYmBEr3onylybQ4PLYuChDYs2v9 eTavTvW1dcUZPumHUusKC+HEUdeQHDRtJNYkUB+Kv37TZugwtPU0OLMIGv0SOXNsPF 2iRJ2C3KSBGXA== Message-ID: Date: Sat, 7 Nov 2026 14:17:57 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: mm/mremap: F_SEAL_FUTURE_WRITE can be bypassed via mremap() VMA expansion/duplication To: Junyoung Jang , Andrew Morton , "Liam R . Howlett" , Lorenzo Stoakes , Hugh Dickins Cc: Vlastimil Babka , Jann Horn , Pedro Falcato , Baolin Wang , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20261107030708.1031977-1-graypanda.inzag@gmail.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20261107030708.1031977-1-graypanda.inzag@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/7/26 04:07, Junyoung Jang wrote: > Hello, Hi, > > I found a reproducible F_SEAL_FUTURE_WRITE seal-policy bypass. A process > holding a one-page shared writable memfd mapping created before the seal can > use mremap() after the seal to gain writable access to additional file pages. F_SEAL_FUTURE_WRITE is not really range-aware. What makes you believe that it would be? I'd say it's expected that if someone has write access to the memfd, it has write access to the whole thing, not just some subset that was obtained through the initial mmap. Any documentation that made you believe that it works that way? -- Cheers, David