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, 39 insertions, 0 deletions

diff --git a/net/mpls/Kconfig b/net/mpls/Kconfig
new file mode 100644
index 000000000..d672ab72a
--- /dev/null
+++ b/net/mpls/Kconfig
@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# MPLS configuration
+#
+
+menuconfig MPLS
+	bool "MultiProtocol Label Switching"
+	default n
+	help
+	  MultiProtocol Label Switching routes packets through logical
+	  circuits.  Originally conceived as a way of routing packets at
+	  hardware speeds (before hardware was capable of routing ipv4 packets),
+	  MPLS remains a simple way of making tunnels.
+
+	  If you have not heard of MPLS you probably want to say N here.
+
+if MPLS
+
+config NET_MPLS_GSO
+	tristate "MPLS: GSO support"
+	help
+	 This is helper module to allow segmentation of non-MPLS GSO packets
+	 that have had MPLS stack entries pushed onto them and thus
+	 become MPLS GSO packets.
+
+config MPLS_ROUTING
+	tristate "MPLS: routing support"
+	depends on NET_IP_TUNNEL || NET_IP_TUNNEL=n
+	depends on PROC_SYSCTL
+	help
+	 Add support for forwarding of mpls packets.
+
+config MPLS_IPTUNNEL
+	tristate "MPLS: IP over MPLS tunnel support"
+	depends on LWTUNNEL && MPLS_ROUTING
+	help
+	 mpls ip tunnel support.
+
+endif # MPLS