openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 88 insertions, 0 deletions

diff --git a/include/drm/drm_ras.h b/include/drm/drm_ras.h
new file mode 100644
index 000000000..0beede3dd
--- /dev/null
+++ b/include/drm/drm_ras.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2026 Intel Corporation
+ */
+
+#ifndef __DRM_RAS_H__
+#define __DRM_RAS_H__
+
+#include <linux/types.h>
+
+#include <uapi/drm/drm_ras.h>
+
+/**
+ * struct drm_ras_node - A DRM RAS Node
+ */
+struct drm_ras_node {
+	/** @id: Unique identifier for the node. Dynamically assigned. */
+	u32 id;
+	/**
+	 * @device_name: Human-readable name of the device. Given by the driver.
+	 */
+	const char *device_name;
+	/** @node_name: Human-readable name of the node. Given by the driver. */
+	const char *node_name;
+	/** @type: Type of the node (enum drm_ras_node_type). */
+	enum drm_ras_node_type type;
+
+	/* Error-Counter Related Callback and Variables */
+
+	/** @error_counter_range: Range of valid Error IDs for this node. */
+	struct {
+		/** @first: First valid Error ID. */
+		u32 first;
+		/** @last: Last valid Error ID. Mandatory entry. */
+		u32 last;
+	} error_counter_range;
+
+	/**
+	 * @query_error_counter:
+	 *
+	 * This callback is used by drm-ras to query a specific error counter.
+	 * Used for input check and to iterate all error counters in a node.
+	 *
+	 * Driver should expect query_error_counter() to be called with
+	 * error_id from `error_counter_range.first` to
+	 * `error_counter_range.last`.
+	 *
+	 * The @query_error_counter is a mandatory callback for
+	 * error_counter_node.
+	 *
+	 * Returns: 0 on success,
+	 *          -ENOENT when error_id is not supported as an indication that
+	 *                  drm_ras should silently skip this entry. Used for
+	 *                  supporting non-contiguous error ranges.
+	 *                  Driver is responsible for maintaining the list of
+	 *                  supported error IDs in the range of first to last.
+	 *          Other negative values on errors that should terminate the
+	 *          netlink query.
+	 */
+	int (*query_error_counter)(struct drm_ras_node *node, u32 error_id,
+				   const char **name, u32 *val);
+
+	/**
+	 * @clear_error_counter:
+	 *
+	 * This callback is used by drm_ras to clear a specific error counter.
+	 * Driver should implement this callback to support clearing error counters
+	 * of a node.
+	 *
+	 * Returns: 0 on success, negative error code on failure.
+	 */
+	int (*clear_error_counter)(struct drm_ras_node *node, u32 error_id);
+
+	/** @priv: Driver private data */
+	void *priv;
+};
+
+struct drm_device;
+
+#if IS_ENABLED(CONFIG_DRM_RAS)
+int drm_ras_node_register(struct drm_ras_node *node);
+void drm_ras_node_unregister(struct drm_ras_node *node);
+#else
+static inline int drm_ras_node_register(struct drm_ras_node *node) { return 0; }
+static inline void drm_ras_node_unregister(struct drm_ras_node *node) { }
+#endif
+
+#endif