[PATCH] drm/i915: Relax mmap VMA check - Linux-stable-mirror

5 Mar 2019

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

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index a1ad5e137a97..0196ad97adcb 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1593,7 +1593,8 @@ __vma_matches(struct vm_area_struct *vma, struct file *filp,
    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);
 }
/**
-- 
2.19.1


    