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, 23 insertions, 0 deletions

diff --git a/block/partitions/Makefile b/block/partitions/Makefile
new file mode 100644
index 000000000..25d424922
--- /dev/null
+++ b/block/partitions/Makefile
@@ -0,0 +1,23 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the linux kernel.
+#
+
+obj-$(CONFIG_BLOCK) += core.o
+obj-$(CONFIG_ACORN_PARTITION) += acorn.o
+obj-$(CONFIG_AMIGA_PARTITION) += amiga.o
+obj-$(CONFIG_ATARI_PARTITION) += atari.o
+obj-$(CONFIG_AIX_PARTITION) += aix.o
+obj-$(CONFIG_CMDLINE_PARTITION) += cmdline.o
+obj-$(CONFIG_MAC_PARTITION) += mac.o
+obj-$(CONFIG_LDM_PARTITION) += ldm.o
+obj-$(CONFIG_MSDOS_PARTITION) += msdos.o
+obj-$(CONFIG_OF_PARTITION) += of.o
+obj-$(CONFIG_OSF_PARTITION) += osf.o
+obj-$(CONFIG_SGI_PARTITION) += sgi.o
+obj-$(CONFIG_SUN_PARTITION) += sun.o
+obj-$(CONFIG_ULTRIX_PARTITION) += ultrix.o
+obj-$(CONFIG_IBM_PARTITION) += ibm.o
+obj-$(CONFIG_EFI_PARTITION) += efi.o
+obj-$(CONFIG_KARMA_PARTITION) += karma.o
+obj-$(CONFIG_SYSV68_PARTITION) += sysv68.o