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, 195 insertions, 0 deletions

diff --git a/Documentation/netlink/specs/rt-addr.yaml b/Documentation/netlink/specs/rt-addr.yaml
new file mode 100644
index 000000000..163a106c4
--- /dev/null
+++ b/Documentation/netlink/specs/rt-addr.yaml
@@ -0,0 +1,195 @@
+# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+---
+name: rt-addr
+protocol: netlink-raw
+uapi-header: linux/rtnetlink.h
+protonum: 0
+
+doc: >-
+  Address configuration over rtnetlink.
+
+definitions:
+  -
+    name: ifaddrmsg
+    type: struct
+    members:
+      -
+        name: ifa-family
+        type: u8
+      -
+        name: ifa-prefixlen
+        type: u8
+      -
+        name: ifa-flags
+        type: u8
+        enum: ifa-flags
+        enum-as-flags: true
+      -
+        name: ifa-scope
+        type: u8
+      -
+        name: ifa-index
+        type: u32
+  -
+    name: ifa-cacheinfo
+    type: struct
+    members:
+      -
+        name: ifa-prefered
+        type: u32
+      -
+        name: ifa-valid
+        type: u32
+      -
+        name: cstamp
+        type: u32
+      -
+        name: tstamp
+        type: u32
+
+  -
+    name: ifa-flags
+    type: flags
+    name-prefix: ifa-f-
+    enum-name:
+    entries:
+      -
+        name: secondary
+      -
+        name: nodad
+      -
+        name: optimistic
+      -
+        name: dadfailed
+      -
+        name: homeaddress
+      -
+        name: deprecated
+      -
+        name: tentative
+      -
+        name: permanent
+      -
+        name: managetempaddr
+      -
+        name: noprefixroute
+      -
+        name: mcautojoin
+      -
+        name: stable-privacy
+
+attribute-sets:
+  -
+    name: addr-attrs
+    name-prefix: ifa-
+    attributes:
+      -
+        name: address
+        type: binary
+        display-hint: ipv4-or-v6
+      -
+        name: local
+        type: binary
+        display-hint: ipv4-or-v6
+      -
+        name: label
+        type: string
+      -
+        name: broadcast
+        type: u32
+        byte-order: big-endian
+        display-hint: ipv4
+      -
+        name: anycast
+        type: binary
+      -
+        name: cacheinfo
+        type: binary
+        struct: ifa-cacheinfo
+      -
+        name: multicast
+        type: binary
+      -
+        name: flags
+        type: u32
+        enum: ifa-flags
+        enum-as-flags: true
+      -
+        name: rt-priority
+        type: u32
+      -
+        name: target-netnsid
+        type: binary
+      -
+        name: proto
+        type: u8
+
+
+operations:
+  fixed-header: ifaddrmsg
+  enum-model: directional
+  name-prefix: rtm-
+  list:
+    -
+      name: newaddr
+      doc: Add new address
+      attribute-set: addr-attrs
+      do:
+        request:
+          value: 20
+          attributes: &ifaddr-all
+            - address
+            - label
+            - local
+            - cacheinfo
+    -
+      name: deladdr
+      doc: Remove address
+      attribute-set: addr-attrs
+      do:
+        request:
+          value: 21
+          attributes:
+            - address
+            - local
+    -
+      name: getaddr
+      doc: Dump address information.
+      attribute-set: addr-attrs
+      dump:
+        request:
+          value: 22
+          attributes: []
+        reply:
+          value: 20
+          attributes: *ifaddr-all
+    -
+      name: getmulticast
+      doc: Get / dump IPv4/IPv6 multicast addresses.
+      attribute-set: addr-attrs
+      fixed-header: ifaddrmsg
+      do:
+        request:
+          value: 58
+          attributes: []
+        reply:
+          value: 58
+          attributes: &mcaddr-attrs
+            - multicast
+            - cacheinfo
+      dump:
+        request:
+          value: 58
+          attributes: []
+        reply:
+          value: 58
+          attributes: *mcaddr-attrs
+
+mcast-groups:
+  list:
+    -
+      name: rtnlgrp-ipv4-ifaddr
+      value: 5
+    -
+      name: rtnlgrp-ipv6-ifaddr
+      value: 9