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, 28 insertions, 0 deletions

diff --git a/Documentation/gpu/v3d.rst b/Documentation/gpu/v3d.rst
new file mode 100644
index 000000000..543f7fbf5
--- /dev/null
+++ b/Documentation/gpu/v3d.rst
@@ -0,0 +1,28 @@
+=====================================
+ drm/v3d Broadcom V3D Graphics Driver
+=====================================
+
+.. kernel-doc:: drivers/gpu/drm/v3d/v3d_drv.c
+   :doc: Broadcom V3D Graphics Driver
+
+GPU buffer object (BO) management
+---------------------------------
+
+.. kernel-doc:: drivers/gpu/drm/v3d/v3d_bo.c
+   :doc: V3D GEM BO management support
+
+Address space management
+===========================================
+.. kernel-doc:: drivers/gpu/drm/v3d/v3d_mmu.c
+   :doc: Broadcom V3D MMU
+
+GPU Scheduling
+===========================================
+.. kernel-doc:: drivers/gpu/drm/v3d/v3d_sched.c
+   :doc: Broadcom V3D scheduling
+
+Interrupts
+--------------
+
+.. kernel-doc:: drivers/gpu/drm/v3d/v3d_irq.c
+   :doc: Interrupt management for the V3D engine