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, 24 insertions, 0 deletions

diff --git a/net/mctp/Kconfig b/net/mctp/Kconfig
new file mode 100644
index 000000000..d8d3413a3
--- /dev/null
+++ b/net/mctp/Kconfig
@@ -0,0 +1,24 @@
+
+menuconfig MCTP
+	depends on NET
+	bool "MCTP core protocol support"
+	help
+	  Management Component Transport Protocol (MCTP) is an in-system
+	  protocol for communicating between management controllers and
+	  their managed devices (peripherals, host processors, etc.). The
+	  protocol is defined by DMTF specification DSP0236.
+
+	  This option enables core MCTP support. For communicating with other
+	  devices, you'll want to enable a driver for a specific hardware
+	  channel.
+
+config MCTP_TEST
+        bool "MCTP core tests" if !KUNIT_ALL_TESTS
+        select MCTP_FLOWS
+        depends on MCTP=y && KUNIT=y
+        default KUNIT_ALL_TESTS
+
+config MCTP_FLOWS
+	bool
+	depends on MCTP
+	select SKB_EXTENSIONS