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, 44 insertions, 0 deletions

diff --git a/tools/perf/ui/keysyms.c b/tools/perf/ui/keysyms.c
new file mode 100644
index 000000000..b64564b07
--- /dev/null
+++ b/tools/perf/ui/keysyms.c
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include "keysyms.h"
+#include <linux/ctype.h>
+#include <linux/kernel.h>
+
+const char *key_name(int key, char *bf, size_t size)
+{
+	if (isprint(key)) {
+		scnprintf(bf, size, "%c", key); 
+	} else if (key < 32) {
+		scnprintf(bf, size, "Ctrl+%c", key + '@'); 
+	} else {
+		const char *name = NULL;
+
+		switch (key) {
+		case K_DOWN:	name = "Down";	    break;
+		case K_END:	name = "End";	    break;
+		case K_ENTER:	name = "Enter";	    break;
+		case K_ESC:	name = "ESC";	    break;
+		case K_F1:	name = "F1";	    break;
+		case K_HOME:	name = "Home";	    break;
+		case K_LEFT:	name = "Left";	    break;
+		case K_PGDN:	name = "PgDown";    break;
+		case K_PGUP:	name = "PgUp";	    break;
+		case K_RIGHT:	name = "Right";	    break;
+		case K_TAB:	name = "Tab";	    break;
+		case K_UNTAB:	name = "Untab";	    break;
+		case K_UP:	name = "Up";	    break;
+		case K_BKSPC:	name = "Backspace"; break;
+		case K_DEL:	name = "Del";	    break;
+		default:
+			if (key >= SL_KEY_F(1) && key <= SL_KEY_F(63))
+				scnprintf(bf, size, "F%d", key - SL_KEY_F(0));
+			else
+				scnprintf(bf, size, "Unknown (%d)", key);
+		}
+
+		if (name)
+			scnprintf(bf, size, "%s", name);
+	}
+
+	return bf;
+}