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, 26 insertions, 0 deletions

diff --git a/sound/firewire/lib.h b/sound/firewire/lib.h
new file mode 100644
index 000000000..664dfdb9e
--- /dev/null
+++ b/sound/firewire/lib.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef SOUND_FIREWIRE_LIB_H_INCLUDED
+#define SOUND_FIREWIRE_LIB_H_INCLUDED
+
+#include <linux/firewire-constants.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <sound/rawmidi.h>
+
+struct fw_unit;
+
+#define FW_GENERATION_MASK	0x00ff
+#define FW_FIXED_GENERATION	0x0100
+#define FW_QUIET		0x0200
+
+int snd_fw_transaction(struct fw_unit *unit, int tcode,
+		       u64 offset, void *buffer, size_t length,
+		       unsigned int flags);
+
+/* returns true if retrying the transaction would not make sense */
+static inline bool rcode_is_permanent_error(int rcode)
+{
+	return rcode == RCODE_TYPE_ERROR || rcode == RCODE_ADDRESS_ERROR;
+}
+
+#endif