Messages in this thread | | | Subject | Re: [PATCH v3 1/9] mm: Introduce new vm_insert_range API | From | Robin Murphy <> | Date | Fri, 7 Dec 2018 21:10:00 +0000 |
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On 2018-12-07 7:28 pm, Souptick Joarder wrote: > On Fri, Dec 7, 2018 at 10:41 PM Matthew Wilcox <willy@infradead.org> wrote: >> >> On Fri, Dec 07, 2018 at 03:34:56PM +0000, Robin Murphy wrote: >>>> +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr, >>>> + struct page **pages, unsigned long page_count) >>>> +{ >>>> + unsigned long uaddr = addr; >>>> + int ret = 0, i; >>> >>> Some of the sites being replaced were effectively ensuring that vma and >>> pages were mutually compatible as an initial condition - would it be worth >>> adding something here for robustness, e.g.: >>> >>> + if (page_count != vma_pages(vma)) >>> + return -ENXIO; >> >> I think we want to allow this to be used to populate part of a VMA. >> So perhaps: >> >> if (page_count > vma_pages(vma)) >> return -ENXIO; > > Ok, This can be added. > > I think Patch [2/9] is the only leftover place where this > check could be removed.
Right, 9/9 could also have relied on my stricter check here, but since it's really testing whether it actually managed to allocate vma_pages() worth of pages earlier, Matthew's more lenient version won't help for that one. (Why privcmd_buf_mmap() doesn't clean up and return an error as soon as that allocation loop fails, without taking the mutex under which it still does a bunch more pointless work to only undo it again, is a mind-boggling mystery, but that's not our problem here...)
Robin.
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