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, 46 insertions, 0 deletions

diff --git a/include/dt-bindings/clock/berlin2.h b/include/dt-bindings/clock/berlin2.h
new file mode 100644
index 000000000..b07b8efab
--- /dev/null
+++ b/include/dt-bindings/clock/berlin2.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Berlin2 BG2/BG2CD clock tree IDs
+ */
+
+#define CLKID_SYS		0
+#define CLKID_CPU		1
+#define CLKID_DRMFIGO		2
+#define CLKID_CFG		3
+#define CLKID_GFX		4
+#define CLKID_ZSP		5
+#define CLKID_PERIF		6
+#define CLKID_PCUBE		7
+#define CLKID_VSCOPE		8
+#define CLKID_NFC_ECC		9
+#define CLKID_VPP		10
+#define CLKID_APP		11
+#define CLKID_AUDIO0		12
+#define CLKID_AUDIO2		13
+#define CLKID_AUDIO3		14
+#define CLKID_AUDIO1		15
+#define CLKID_GFX3D_CORE	16
+#define CLKID_GFX3D_SYS		17
+#define CLKID_ARC		18
+#define CLKID_VIP		19
+#define CLKID_SDIO0XIN		20
+#define CLKID_SDIO1XIN		21
+#define CLKID_GFX3D_EXTRA	22
+#define CLKID_GC360		23
+#define CLKID_SDIO_DLLMST	24
+#define CLKID_GETH0		25
+#define CLKID_GETH1		26
+#define CLKID_SATA		27
+#define CLKID_AHBAPB		28
+#define CLKID_USB0		29
+#define CLKID_USB1		30
+#define CLKID_PBRIDGE		31
+#define CLKID_SDIO0		32
+#define CLKID_SDIO1		33
+#define CLKID_NFC		34
+#define CLKID_SMEMC		35
+#define CLKID_AUDIOHD		36
+#define CLKID_VIDEO0		37
+#define CLKID_VIDEO1		38
+#define CLKID_VIDEO2		39
+#define CLKID_TWD		40