[Intel-gfx] [PATCH] drm/i915: Defend against userspace creating a gem object with size==0

[Chris Wilson]

We currently only round up the userspace size to the next page. We
assume that userspace hasn't made a mistake and requested a zero-length
gem object and all through our internal code we then presume that every
object is backed by at least a single page. Fix that oversight and
report EINVAL back to userspace if they try to create a zero length
object.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index bceb8ec..ec533c7 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -194,6 +194,8 @@ i915_gem_create(struct drm_file *file,
 	u32 handle;
 
 	size = roundup(size, PAGE_SIZE);
+	if (size == 0)
+		return -EINVAL;
 
 	/* Allocate the new object */
 	obj = i915_gem_alloc_object(dev, size);
-- 
1.7.5.4