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, 18 insertions, 0 deletions

diff --git a/drivers/bcma/Makefile b/drivers/bcma/Makefile
new file mode 100644
index 000000000..f8c37de35
--- /dev/null
+++ b/drivers/bcma/Makefile
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0
+bcma-y					+= main.o scan.o core.o sprom.o
+bcma-y					+= driver_chipcommon.o driver_chipcommon_pmu.o
+bcma-y					+= driver_chipcommon_b.o
+bcma-$(CONFIG_BCMA_PFLASH)		+= driver_chipcommon_pflash.o
+bcma-$(CONFIG_BCMA_SFLASH)		+= driver_chipcommon_sflash.o
+bcma-$(CONFIG_BCMA_NFLASH)		+= driver_chipcommon_nflash.o
+bcma-$(CONFIG_BCMA_DRIVER_PCI)		+= driver_pci.o
+bcma-$(CONFIG_BCMA_DRIVER_PCI)		+= driver_pcie2.o
+bcma-$(CONFIG_BCMA_DRIVER_PCI_HOSTMODE)	+= driver_pci_host.o
+bcma-$(CONFIG_BCMA_DRIVER_MIPS)		+= driver_mips.o
+bcma-$(CONFIG_BCMA_DRIVER_GMAC_CMN)	+= driver_gmac_cmn.o
+bcma-$(CONFIG_BCMA_DRIVER_GPIO)		+= driver_gpio.o
+bcma-$(CONFIG_BCMA_HOST_PCI)		+= host_pci.o
+bcma-$(CONFIG_BCMA_HOST_SOC)		+= host_soc.o
+obj-$(CONFIG_BCMA)			+= bcma.o
+
+ccflags-$(CONFIG_BCMA_DEBUG)		:= -DDEBUG