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, 22 insertions, 0 deletions

diff --git a/net/6lowpan/Makefile b/net/6lowpan/Makefile
new file mode 100644
index 000000000..2247b96db
--- /dev/null
+++ b/net/6lowpan/Makefile
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_6LOWPAN) += 6lowpan.o
+
+6lowpan-y := core.o iphc.o nhc.o ndisc.o
+6lowpan-$(CONFIG_6LOWPAN_DEBUGFS) += debugfs.o
+
+#rfc6282 nhcs
+obj-$(CONFIG_6LOWPAN_NHC_DEST) += nhc_dest.o
+obj-$(CONFIG_6LOWPAN_NHC_FRAGMENT) += nhc_fragment.o
+obj-$(CONFIG_6LOWPAN_NHC_HOP) += nhc_hop.o
+obj-$(CONFIG_6LOWPAN_NHC_IPV6) += nhc_ipv6.o
+obj-$(CONFIG_6LOWPAN_NHC_MOBILITY) += nhc_mobility.o
+obj-$(CONFIG_6LOWPAN_NHC_ROUTING) += nhc_routing.o
+obj-$(CONFIG_6LOWPAN_NHC_UDP) += nhc_udp.o
+
+#rfc7400 ghcs
+obj-$(CONFIG_6LOWPAN_GHC_EXT_HDR_HOP) += nhc_ghc_ext_hop.o
+obj-$(CONFIG_6LOWPAN_GHC_UDP) += nhc_ghc_udp.o
+obj-$(CONFIG_6LOWPAN_GHC_ICMPV6) += nhc_ghc_icmpv6.o
+obj-$(CONFIG_6LOWPAN_GHC_EXT_HDR_DEST) += nhc_ghc_ext_dest.o
+obj-$(CONFIG_6LOWPAN_GHC_EXT_HDR_FRAG) += nhc_ghc_ext_frag.o
+obj-$(CONFIG_6LOWPAN_GHC_EXT_HDR_ROUTE) += nhc_ghc_ext_route.o