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, 80 insertions, 0 deletions

diff --git a/tools/perf/util/config.h b/tools/perf/util/config.h
new file mode 100644
index 000000000..987b47cf5
--- /dev/null
+++ b/tools/perf/util/config.h
@@ -0,0 +1,80 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_CONFIG_H
+#define __PERF_CONFIG_H
+
+#include <stdbool.h>
+#include <linux/list.h>
+
+struct perf_config_item {
+	char *name;
+	char *value;
+	bool from_system_config;
+	struct list_head node;
+};
+
+struct perf_config_section {
+	char *name;
+	struct list_head items;
+	bool from_system_config;
+	struct list_head node;
+};
+
+struct perf_config_set {
+	struct list_head sections;
+};
+
+extern const char *config_exclusive_filename;
+
+typedef int (*config_fn_t)(const char *, const char *, void *);
+
+int perf_default_config(const char *, const char *, void *);
+int perf_config(config_fn_t fn, void *);
+int perf_config_scan(const char *name, const char *fmt, ...) __scanf(2, 3);
+const char *perf_config_get(const char *name);
+int perf_config_set(struct perf_config_set *set,
+		    config_fn_t fn, void *data);
+int perf_config_int(int *dest, const char *, const char *);
+int perf_config_u8(u8 *dest, const char *name, const char *value);
+int perf_config_u64(u64 *dest, const char *, const char *);
+int perf_config_bool(const char *, const char *);
+int config_error_nonbool(const char *);
+const char *perf_etc_perfconfig(void);
+const char *perf_home_perfconfig(void);
+int perf_config_system(void);
+int perf_config_global(void);
+
+struct perf_config_set *perf_config_set__new(void);
+struct perf_config_set *perf_config_set__load_file(const char *file);
+void perf_config_set__delete(struct perf_config_set *set);
+int perf_config_set__collect(struct perf_config_set *set, const char *file_name,
+			     const char *var, const char *value);
+void perf_config__exit(void);
+int perf_config__set_variable(const char *var, const char *value);
+
+/**
+ * perf_config_sections__for_each - iterate thru all the sections
+ * @list: list_head instance to iterate
+ * @section: struct perf_config_section iterator
+ */
+#define perf_config_sections__for_each_entry(list, section)	\
+        list_for_each_entry(section, list, node)
+
+/**
+ * perf_config_items__for_each - iterate thru all the items
+ * @list: list_head instance to iterate
+ * @item: struct perf_config_item iterator
+ */
+#define perf_config_items__for_each_entry(list, item)	\
+        list_for_each_entry(item, list, node)
+
+/**
+ * perf_config_set__for_each - iterate thru all the config section-item pairs
+ * @set: evlist instance to iterate
+ * @section: struct perf_config_section iterator
+ * @item: struct perf_config_item iterator
+ */
+#define perf_config_set__for_each_entry(set, section, item)			\
+	perf_config_sections__for_each_entry(&set->sections, section)		\
+	perf_config_items__for_each_entry(&section->items, item)
+
+#endif /* __PERF_CONFIG_H */