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b=fVY1XiJC4Vf5g8jFDmB0ti3FWZ4F99IgchLrZtSH409dEUffRwgmLvXwI7b2csASg 09bJ6DGCH1f7mv2Sy/PZoc60O+YtGZSwsT5AMbTLKSwnQHWetxRf+G1peI3P+WKRkX UqaDP793FuN5d8rp88SEawiQ9QUL2QjptcOmf8h3p5ORacS/vmtMJJYUbXNWjQCjL1 hfwDdMcDxfDfMLdfGjtpQNuZGcTWcDwhtFUtNgBeXzaCLitfNDxCYDKD29H/L/HYas VgrXZE4aGenFr4+BqS2lZyQCLelCVCrvU+60/Ewq0WliMIrkpK/5TShV9X943/7MXL fGVUwPYPWOWBg== Message-ID: <06c15d6b-444f-46f2-9341-84d8afc1afc0@kernel.org> Date: Thu, 10 Sep 2026 10:16:43 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/1] mm/memory: constrain generic_access_phys() to page boundary To: Ren Wei , linux-mm@kvack.org Cc: akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, notasas@gmail.com, vega@nebusec.ai, rakukuip@gmail.com References: 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: u5wexcwps37cmwmqq5ycxga4i6hug35q X-Rspamd-Queue-Id: 785EE100003 X-Rspamd-Server: rspam07 X-HE-Tag: 1789028210-415004 X-HE-Meta: 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 32+QgD2o FxKdV6kBLQji1UryJLz/86oXpZOzZzas6mmWRTEec9i5Ep5zOl0//oaHhq85fwEy8rysszecWNkZ/Y17fjfO4/opJ3BnlU4/T9pGjUM6ZJu2MNtMcMMjTiGOqPLpCcjdVmNPnUMiZ3nMetQSg4/yqXAF2CZQ4RbFGiF0WY8KgwRxwyobjJ0RAAiev2u1AIfVxtPYjNlPyQmvHJY/msiiQOcz2es5sUgvSAGzTquHtfHcfHd0BZSigaCJBxj1FRRjK/5/543XB3Tar/vdags4hUkFlYKV29L7wUQVzx2GidadAQr+6tCpdn34XHMzQFA9Mk5jwsweCjZVJF/Wle8tOpsw/3fIQSk9LoMsM Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/10/26 05:42, Ren Wei wrote: > From: Luxiao Xu > > generic_access_phys() improperly validates the memory access range: it > only validates the start address using follow_pfnmap_start() and passes > PAGE_ALIGN(len + offset) to ioremap_prot(). > > This poses two problems: > 1. In PFNMAP VMAs, consecutive virtual pages are not guaranteed to be > physically contiguous, and individual PTEs may have different access > permissions or writability. > 2. The mapping may cross VMA boundaries if len extends beyond vma->vm_end. > > Constrain the access in generic_access_phys() to at most the current page > boundary (PAGE_SIZE - offset) and map only a single PAGE_SIZE via > ioremap_prot(). Since the caller __access_remote_vm() already loops over > the requested length and handles partial transfers, it will naturally > iterate over the remaining pages. > > Also add a missing (resource_size_t) cast during PFN re-validation to avoid > truncation on 32-bit PAE systems. > > Fixes: 9cb12d7b4cca ("mm/memory.c: actually remap enough memory") > Cc: stable@vger.kernel.org > Reported-by: Vega > Assisted-by: LLM > Suggested-by: David Hildenbrand > Signed-off-by: Luxiao Xu > Signed-off-by: Ren Wei > --- Yes, LGTM! Acked-by: David Hildenbrand (Arm) -- Cheers, David