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 gKTegjhi 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000873, 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 Tue, Jan 14, 2025 at 06:22:14PM +0000, Matthew Wilcox wrote: > On Tue, Jan 14, 2025 at 06:19:32PM +0000, Lorenzo Stoakes wrote: > > I see shmem_zero_page() does change vma->vm_page, this is broken... ugh. I > > I think you mean shmem_zero_setup() and vma->vm_file, right? Yes, correct. Sorry it's late here and it's showing haha! The reason I am concerned about this is because we thread mmap state through the operation which has a separate file pointer which this makes into a potential UAF. Will audit all this and for any other problematic .mmap() callback behaviour. My view is ideally this should be a callback with a const pointer to the VMA (or some other mechanism, perhaps) which accepts a change in _permitted_ fields only. The 'anything could happen and anybody could manipulate any field of the VMA' in this callback is highly problematic. But we definitely shouldn't be adding a _new_ case here.