[Intel-gfx] [PATCH 4.9 085/118] drm/i915: Relax mmap VMA check

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit ca22f32a6296cbfa29de56328c8505560a18cfa8 ]

Legacy behaviour was to allow non-page-aligned mmap requests, as does the
linux mmap(2) implementation by virtue of automatically rounding up for
the caller.

To avoid breaking legacy userspace relax the newly introduced fix.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Fixes: 5c4604e757ba ("drm/i915: Prevent a race during I915_GEM_MMAP ioctl with WC set")
Reported-by: Guenter Roeck <linux at roeck-us.net>
Cc: Adam Zabrocki <adamza at microsoft.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: <stable at vger.kernel.org> # v4.0+
Cc: Akash Goel <akash.goel at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: intel-gfx at lists.freedesktop.org
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190305110409.28633-1-tvrtko.ursulin@linux.intel.com
(cherry picked from commit a90e1948efb648f567444f87f3c19b2a0787affd)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/gpu/drm/i915/i915_gem.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1600,7 +1600,8 @@ __vma_matches(struct vm_area_struct *vma
 	if (vma->vm_file != filp)
 		return false;
 
-	return vma->vm_start == addr && (vma->vm_end - vma->vm_start) == size;
+	return vma->vm_start == addr &&
+	       (vma->vm_end - vma->vm_start) == PAGE_ALIGN(size);
 }
 
 /**