1 files changed, 61 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_user_extensions.c b/drivers/gpu/drm/i915/i915_user_extensions.c
new file mode 100644
index 000000000000..c822d0aafd2d
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_user_extensions.c
@@ -0,0 +1,61 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2018 Intel Corporation
+ */
+
+#include <linux/nospec.h>
+#include <linux/sched/signal.h>
+#include <linux/uaccess.h>
+
+#include <uapi/drm/i915_drm.h>
+
+#include "i915_user_extensions.h"
+#include "i915_utils.h"
+
+int i915_user_extensions(struct i915_user_extension __user *ext,
+			 const i915_user_extension_fn *tbl,
+			 unsigned int count,
+			 void *data)
+{
+	unsigned int stackdepth = 512;
+
+	while (ext) {
+		int i, err;
+		u32 name;
+		u64 next;
+
+		if (!stackdepth--) /* recursion vs useful flexibility */
+			return -E2BIG;
+
+		err = check_user_mbz(&ext->flags);
+		if (err)
+			return err;
+
+		for (i = 0; i < ARRAY_SIZE(ext->rsvd); i++) {
+			err = check_user_mbz(&ext->rsvd[i]);
+			if (err)
+				return err;
+		}
+
+		if (get_user(name, &ext->name))
+			return -EFAULT;
+
+		err = -EINVAL;
+		if (name < count) {
+			name = array_index_nospec(name, count);
+			if (tbl[name])
+				err = tbl[name](ext, data);
+		}
+		if (err)
+			return err;
+
+		if (get_user(next, &ext->next_extension) ||
+		    overflows_type(next, ext))
+			return -EFAULT;
+
+		ext = u64_to_user_ptr(next);
+	}
+
+	return 0;
+}