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/reset/spacemit/Kconfig b/drivers/reset/spacemit/Kconfig
new file mode 100644
index 000000000..545d6b41c
--- /dev/null
+++ b/drivers/reset/spacemit/Kconfig
@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+menu "Reset support for SpacemiT platforms"
+	depends on ARCH_SPACEMIT || COMPILE_TEST
+
+config RESET_SPACEMIT_COMMON
+	tristate
+	select AUXILIARY_BUS
+	help
+	  Common reset controller infrastructure for SpacemiT SoCs.
+	  This provides shared code and helper functions used by
+	  reset drivers for various SpacemiT SoC families.
+
+config RESET_SPACEMIT_K1
+	tristate "Support for SpacemiT K1 SoC"
+	depends on SPACEMIT_K1_CCU
+	select RESET_SPACEMIT_COMMON
+	default SPACEMIT_K1_CCU
+	help
+	  Support for reset controller in SpacemiT K1 SoC.
+	  This driver works with the SpacemiT K1 clock controller
+	  unit (CCU) driver to provide reset control functionality
+	  for various peripherals and subsystems in the SoC.
+
+config RESET_SPACEMIT_K3
+	tristate "Support for SpacemiT K3 SoC"
+	depends on SPACEMIT_K3_CCU
+	select RESET_SPACEMIT_COMMON
+	default SPACEMIT_K3_CCU
+	help
+	  Support for reset controller in SpacemiT K3 SoC.
+	  This driver works with the SpacemiT K3 clock controller
+	  unit (CCU) driver to provide reset control functionality
+	  for various peripherals and subsystems in the SoC.
+
+endmenu