drm/i915: Relax mmap VMA check

tursulin · rodrigovivi · commit ca22f32a6296 · 2019-03-08T09:52:55.000-08:00
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: 5c4604e ("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 Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/msgid/20190305110409.28633-1-tvrtko.ursulin@linux.intel.com (cherry picked from commit a90e194) Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
@@ -1688,7 +1688,8 @@ __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);
 }
 
 /**

Original file line number	Diff line number	Diff line change
`@@ -1688,7 +1688,8 @@ __vma_matches(struct vm_area_struct vma, struct file filp,`
`1688`	`1688`	`if (vma->vm_file != filp)`
`1689`	`1689`	`return false;`
`1690`	`1690`
`1691`		`- return vma->vm_start == addr && (vma->vm_end - vma->vm_start) == size;`
	`1691`	`+ return vma->vm_start == addr &&`
	`1692`	`+ (vma->vm_end - vma->vm_start) == PAGE_ALIGN(size);`
`1692`	`1693`	`}`
`1693`	`1694`
`1694`	`1695`	`/**`