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, 32 insertions, 0 deletions

diff --git a/drivers/clk/versatile/Kconfig b/drivers/clk/versatile/Kconfig
new file mode 100644
index 000000000..403f16495
--- /dev/null
+++ b/drivers/clk/versatile/Kconfig
@@ -0,0 +1,32 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+menu "Clock driver for ARM Reference designs"
+	depends on HAS_IOMEM
+	depends on ARM || ARM64 || COMPILE_TEST
+
+config CLK_ICST
+	bool "Clock driver for ARM Reference designs ICST"
+	select REGMAP_MMIO
+	help
+	  Supports clocking on ARM Reference designs:
+	  - Integrator/AP and Integrator/CP
+	  - RealView PB1176, EB, PB11MP and PBX
+
+config CLK_SP810
+	bool "Clock driver for ARM SP810 System Controller"
+	default y if (ARCH_VEXPRESS && ARM)
+	help
+	  Supports clock muxing (REFCLK/TIMCLK to TIMERCLKEN0-3) capabilities
+	  of the ARM SP810 System Controller cell.
+
+config CLK_VEXPRESS_OSC
+	tristate "Clock driver for Versatile Express OSC clock generators"
+	depends on VEXPRESS_CONFIG
+	select REGMAP_MMIO
+	default y if ARCH_VEXPRESS
+	help
+	  Simple regmap-based driver driving clock generators on Versatile
+	  Express platforms hidden behind its configuration infrastructure,
+	  commonly known as OSCs.
+
+endmenu