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, 78 insertions, 0 deletions

diff --git a/Documentation/networking/ipv6.rst b/Documentation/networking/ipv6.rst
new file mode 100644
index 000000000..ba09c2f2d
--- /dev/null
+++ b/Documentation/networking/ipv6.rst
@@ -0,0 +1,78 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====
+IPv6
+====
+
+
+Options for the ipv6 module are supplied as parameters at load time.
+
+Module options may be given as command line arguments to the insmod
+or modprobe command, but are usually specified in either
+``/etc/modules.d/*.conf`` configuration files, or in a distro-specific
+configuration file.
+
+The available ipv6 module parameters are listed below.  If a parameter
+is not specified the default value is used.
+
+The parameters are as follows:
+
+disable
+
+	Specifies whether to load the IPv6 module, but disable all
+	its functionality.  This might be used when another module
+	has a dependency on the IPv6 module being loaded, but no
+	IPv6 addresses or operations are desired.
+
+	The possible values and their effects are:
+
+	0
+		IPv6 is enabled.
+
+		This is the default value.
+
+	1
+		IPv6 is disabled.
+
+		No IPv6 addresses will be added to interfaces, and
+		it will not be possible to open an IPv6 socket.
+
+		A reboot is required to enable IPv6.
+
+autoconf
+
+	Specifies whether to enable IPv6 address autoconfiguration
+	on all interfaces.  This might be used when one does not wish
+	for addresses to be automatically generated from prefixes
+	received in Router Advertisements.
+
+	The possible values and their effects are:
+
+	0
+		IPv6 address autoconfiguration is disabled on all interfaces.
+
+		Only the IPv6 loopback address (::1) and link-local addresses
+		will be added to interfaces.
+
+	1
+		IPv6 address autoconfiguration is enabled on all interfaces.
+
+		This is the default value.
+
+disable_ipv6
+
+	Specifies whether to disable IPv6 on all interfaces.
+	This might be used when no IPv6 addresses are desired.
+
+	The possible values and their effects are:
+
+	0
+		IPv6 is enabled on all interfaces.
+
+		This is the default value.
+
+	1
+		IPv6 is disabled on all interfaces.
+
+		No IPv6 addresses will be added to interfaces.
+