diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 4ac454a..83876a1 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -2094,6 +2094,11 @@
 			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");
@@ -2101,6 +2106,9 @@
 			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 6598fb7..9816590 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -829,6 +829,7 @@
 
 #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;
 };