[PATCH 1/2] drm/i915: Reject unknown syncobj flags

Tvrtko Ursulin
2017-10-31T10:23:33Z

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

We have to reject unknown flags for uAPI considerations, and also
because the curent implementation limits their i915 storage space
to two bits.

v2: (Chris Wilson)
* Fix fail in ABI check.
* Added unknown flags and BUILD_BUG_ON.

v3:
* Use ARCH_KMALLOC_MINALIGN instead of alignof. (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: cf6e7bac6357 ("drm/i915: Add support for drm syncobjs")
Cc: Jason Ekstrand <jason@jlekstrand.net>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
---
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 8 ++++++++
include/uapi/drm/i915_drm.h | 1 +
2 files changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 3d7190764f10..a53be7d01055 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -2100,6 +2100,11 @@ get_fence_array(struct drm_i915_gem_execbuffer2 *args,
goto err;
}

+ if (fence.flags & __I915_EXEC_FENCE_UNKNOWN_FLAGS) {
+ err = -EINVAL;
+ goto err;
+ }
+
syncobj = drm_syncobj_find(file, fence.handle);
if (!syncobj) {
DRM_DEBUG("Invalid syncobj handle provided\n");
@@ -2107,6 +2112,9 @@ get_fence_array(struct drm_i915_gem_execbuffer2 *args,
goto err;
}

+ BUILD_BUG_ON(~(ARCH_KMALLOC_MINALIGN - 1) &
+ ~__I915_EXEC_FENCE_UNKNOWN_FLAGS);
+
fences[n] = ptr_pack_bits(syncobj, fence.flags, 2);
}

diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 125bde7d9504..ac3c6503ca27 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -839,6 +839,7 @@ struct drm_i915_gem_exec_fence {

#define I915_EXEC_FENCE_WAIT (1<<0)
#define I915_EXEC_FENCE_SIGNAL (1<<1)
+#define __I915_EXEC_FENCE_UNKNOWN_FLAGS (-(I915_EXEC_FENCE_SIGNAL << 1))
__u32 flags;
};

--
2.9.5