On 7/30/19 2:03 AM, Souptick Joarder wrote: > On Mon, Jul 29, 2019 at 7:06 PM Marek Marczykowski-Górecki > <marmarek@xxxxxxxxxxxxxxxxxxxxxx> wrote: >> On Mon, Jul 29, 2019 at 02:02:54PM +0530, Souptick Joarder wrote: >>> On Mon, Jul 29, 2019 at 1:35 PM Souptick Joarder <jrdr.linux@xxxxxxxxx> wrote: >>>> On Sun, Jul 28, 2019 at 11:36 PM Marek Marczykowski-Górecki >>>> <marmarek@xxxxxxxxxxxxxxxxxxxxxx> wrote: >>>>> On Fri, Feb 15, 2019 at 08:18:31AM +0530, Souptick Joarder wrote: >>>>>> Convert to use vm_map_pages() to map range of kernel >>>>>> memory to user vma. >>>>>> >>>>>> map->count is passed to vm_map_pages() and internal API >>>>>> verify map->count against count ( count = vma_pages(vma)) >>>>>> for page array boundary overrun condition. >>>>> This commit breaks gntdev driver. If vma->vm_pgoff > 0, vm_map_pages >>>>> will: >>>>> - use map->pages starting at vma->vm_pgoff instead of 0 >>>> The actual code ignores vma->vm_pgoff > 0 scenario and mapped >>>> the entire map->pages[i]. Why the entire map->pages[i] needs to be mapped >>>> if vma->vm_pgoff > 0 (in original code) ? >> vma->vm_pgoff is used as index passed to gntdev_find_map_index. It's >> basically (ab)using this parameter for "which grant reference to map". >> >>>> are you referring to set vma->vm_pgoff = 0 irrespective of value passed >>>> from user space ? If yes, using vm_map_pages_zero() is an alternate >>>> option. >> Yes, that should work. > I prefer to use vm_map_pages_zero() to resolve both the issues. Alternatively > the patch can be reverted as you suggested. Let me know you opinion and wait > for feedback from others. > > Boris, would you like to give any feedback ? vm_map_pages_zero() looks good to me. Marek, does it work for you? -boris
