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, 32 insertions, 0 deletions

diff --git a/tools/perf/ui/keysyms.h b/tools/perf/ui/keysyms.h
new file mode 100644
index 000000000..969060edc
--- /dev/null
+++ b/tools/perf/ui/keysyms.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PERF_KEYSYMS_H_
+#define _PERF_KEYSYMS_H_ 1
+
+#include "libslang.h"
+
+#define K_DOWN	SL_KEY_DOWN
+#define K_END	SL_KEY_END
+#define K_ENTER	'\r'
+#define K_ESC	033
+#define K_F1	SL_KEY_F(1)
+#define K_HOME	SL_KEY_HOME
+#define K_LEFT	SL_KEY_LEFT
+#define K_PGDN	SL_KEY_NPAGE
+#define K_PGUP	SL_KEY_PPAGE
+#define K_RIGHT	SL_KEY_RIGHT
+#define K_TAB	'\t'
+#define K_UNTAB	SL_KEY_UNTAB
+#define K_UP	SL_KEY_UP
+#define K_BKSPC 0x7f
+#define K_DEL	SL_KEY_DELETE
+
+/* Not really keys */
+#define K_TIMER	 -1
+#define K_ERROR	 -2
+#define K_RESIZE -3
+#define K_SWITCH_INPUT_DATA -4
+#define K_RELOAD -5
+
+const char *key_name(int key, char *bf, size_t size);
+
+#endif /* _PERF_KEYSYMS_H_ */