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, 41 insertions, 0 deletions

diff --git a/include/crypto/hash_info.h b/include/crypto/hash_info.h
new file mode 100644
index 000000000..d6927739f
--- /dev/null
+++ b/include/crypto/hash_info.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Hash Info: Hash algorithms information
+ *
+ * Copyright (c) 2013 Dmitry Kasatkin <d.kasatkin@samsung.com>
+ */
+
+#ifndef _CRYPTO_HASH_INFO_H
+#define _CRYPTO_HASH_INFO_H
+
+#include <crypto/sha1.h>
+#include <crypto/sha2.h>
+#include <crypto/sha3.h>
+#include <crypto/md5.h>
+#include <crypto/streebog.h>
+
+#include <uapi/linux/hash_info.h>
+
+/* not defined in include/crypto/ */
+#define RMD128_DIGEST_SIZE      16
+#define RMD160_DIGEST_SIZE	20
+#define RMD256_DIGEST_SIZE      32
+#define RMD320_DIGEST_SIZE      40
+
+/* not defined in include/crypto/ */
+#define WP512_DIGEST_SIZE	64
+#define WP384_DIGEST_SIZE	48
+#define WP256_DIGEST_SIZE	32
+
+/* not defined in include/crypto/ */
+#define TGR128_DIGEST_SIZE 16
+#define TGR160_DIGEST_SIZE 20
+#define TGR192_DIGEST_SIZE 24
+
+/* not defined in include/crypto/ */
+#define SM3256_DIGEST_SIZE 32
+
+extern const char *const hash_algo_name[HASH_ALGO__LAST];
+extern const int hash_digest_size[HASH_ALGO__LAST];
+
+#endif /* _CRYPTO_HASH_INFO_H */