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, 88 insertions, 0 deletions

diff --git a/Documentation/crypto/libcrypto-hash.rst b/Documentation/crypto/libcrypto-hash.rst
new file mode 100644
index 000000000..fa4c54236
--- /dev/null
+++ b/Documentation/crypto/libcrypto-hash.rst
@@ -0,0 +1,88 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Hash functions, MACs, and XOFs
+==============================
+
+AES-CMAC and AES-XCBC-MAC
+-------------------------
+
+This API provides support for the AES-CMAC and AES-XCBC-MAC message
+authentication codes.
+
+.. kernel-doc:: include/crypto/aes-cbc-macs.h
+
+BLAKE2b
+-------
+
+This API provides support for the BLAKE2b cryptographic hash function.
+
+.. kernel-doc:: include/crypto/blake2b.h
+
+BLAKE2s
+-------
+
+This API provides support for the BLAKE2s cryptographic hash function.
+
+.. kernel-doc:: include/crypto/blake2s.h
+
+GHASH and POLYVAL
+-----------------
+
+This API provides support for the GHASH and POLYVAL universal hash functions.
+These algorithms are used only as internal components of other algorithms.
+
+.. kernel-doc:: include/crypto/gf128hash.h
+
+MD5
+---
+
+This API provides support for the MD5 cryptographic hash function and HMAC-MD5.
+This algorithm is obsolete and is supported only for backwards compatibility.
+
+.. kernel-doc:: include/crypto/md5.h
+
+NH
+--
+
+This API provides support for the NH universal hash function.  This algorithm is
+used only as an internal component of other algorithms.
+
+.. kernel-doc:: include/crypto/nh.h
+
+Poly1305
+--------
+
+This API provides support for the Poly1305 universal hash function.  This
+algorithm is used only as an internal component of other algorithms.
+
+.. kernel-doc:: include/crypto/poly1305.h
+
+SHA-1
+-----
+
+This API provides support for the SHA-1 cryptographic hash function and
+HMAC-SHA1.  This algorithm is obsolete and is supported only for backwards
+compatibility.
+
+.. kernel-doc:: include/crypto/sha1.h
+
+SHA-2
+-----
+
+This API provides support for the SHA-2 family of cryptographic hash functions,
+including SHA-224, SHA-256, SHA-384, and SHA-512.  This also includes their
+corresponding HMACs: HMAC-SHA224, HMAC-SHA256, HMAC-SHA384, and HMAC-SHA512.
+
+.. kernel-doc:: include/crypto/sha2.h
+
+SHA-3
+-----
+
+The SHA-3 API is documented in :ref:`sha3`.
+
+SM3
+---
+
+This API provides support for the SM3 cryptographic hash function.
+
+.. kernel-doc:: include/crypto/sm3.h