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, 36 insertions, 0 deletions

diff --git a/drivers/interconnect/mediatek/Kconfig b/drivers/interconnect/mediatek/Kconfig
new file mode 100644
index 000000000..9fd3f2170
--- /dev/null
+++ b/drivers/interconnect/mediatek/Kconfig
@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config INTERCONNECT_MTK
+	bool "MediaTek interconnect drivers"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	help
+	  Support for MediaTek's bus interconnect hardware.
+
+config INTERCONNECT_MTK_DVFSRC_EMI
+	tristate "MediaTek DVFSRC EMI interconnect driver"
+	depends on INTERCONNECT_MTK && MTK_DVFSRC
+	help
+	  This is a driver for the MediaTek External Memory Interface
+	  interconnect on SoCs equipped with the integrated Dynamic
+	  Voltage Frequency Scaling Resource Collector (DVFSRC) MCU
+
+config INTERCONNECT_MTK_MT8183
+	tristate "MediaTek MT8183 interconnect driver"
+	depends on INTERCONNECT_MTK_DVFSRC_EMI
+	help
+	  This is a driver for the MediaTek bus interconnect on MT8183-based
+	  platforms.
+
+config INTERCONNECT_MTK_MT8195
+	tristate "MediaTek MT8195 interconnect driver"
+	depends on INTERCONNECT_MTK_DVFSRC_EMI
+	help
+	  This is a driver for the MediaTek bus interconnect on MT8195-based
+	  platforms.
+
+config INTERCONNECT_MTK_MT8196
+	tristate "MediaTek MT8196 interconnect driver"
+	depends on INTERCONNECT_MTK_DVFSRC_EMI
+	help
+	  This is a driver for the MediaTek bus interconnect on MT8196-based
+	  platforms.