Re: [PATCH 4.19.y v2] drm/i915/gem: Fix Virtual Memory mapping boundaries calculation

[Greg KH <greg@kroah.com>]

On Tue, Aug 13, 2024 at 07:09:30PM +0200, Andi Shyti wrote:
> Commit 8bdd9ef7e9b1b2a73e394712b72b22055e0e26c3 upstream.
> 
> Calculating the size of the mapped area as the lesser value
> between the requested size and the actual size does not consider
> the partial mapping offset. This can cause page fault access.
> 
> Fix the calculation of the starting and ending addresses, the
> total size is now deduced from the difference between the end and
> start addresses.
> 
> Additionally, the calculations have been rewritten in a clearer
> and more understandable form.
> 
> Fixes: c58305af1835 ("drm/i915: Use remap_io_mapping() to prefault all PTE in a single pass")
> Reported-by: Jann Horn <jannh@google.com>
> Co-developed-by: Chris Wilson <chris.p.wilson@linux.intel.com>
> Signed-off-by: Chris Wilson <chris.p.wilson@linux.intel.com>
> Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: <stable@vger.kernel.org> # v4.9+
> Reviewed-by: Jann Horn <jannh@google.com>
> Reviewed-by: Jonathan Cavitt <Jonathan.cavitt@intel.com>
> [Joonas: Add Requires: tag]
> Requires: 60a2066c5005 ("drm/i915/gem: Adjust vma offset for framebuffer mmap offset")
> Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Link: https://patchwork.freedesktop.org/patch/msgid/20240802083850.103694-3-andi.shyti@linux.intel.com
> (cherry picked from commit 97b6784753da06d9d40232328efc5c5367e53417)
> Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> ---
> Hi,
> 
> sorry for sending this v2 after I submitted a patch with a
> compilation error. It slipped off a variable (obj_offset) that
> was removed for kernel 4.19.

Much better, now queued up, thanks!

greg k-h