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/misc/ocxl-config.h b/include/misc/ocxl-config.h
new file mode 100644
index 000000000..ccfd3b463
--- /dev/null
+++ b/include/misc/ocxl-config.h
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright 2017 IBM Corp.
+#ifndef _OCXL_CONFIG_H_
+#define _OCXL_CONFIG_H_
+
+/*
+ * This file lists the various constants used to read the
+ * configuration space of an opencapi adapter.
+ *
+ * It follows the specification for opencapi 3.0
+ */
+
+#define OCXL_EXT_CAP_ID_DVSEC                 0x23
+
+#define OCXL_DVSEC_VENDOR_OFFSET              0x4
+#define OCXL_DVSEC_ID_OFFSET                  0x8
+#define OCXL_DVSEC_TL_ID                      0xF000
+#define   OCXL_DVSEC_TL_BACKOFF_TIMERS          0x10
+#define   OCXL_DVSEC_TL_RECV_CAP                0x18
+#define   OCXL_DVSEC_TL_SEND_CAP                0x20
+#define   OCXL_DVSEC_TL_RECV_RATE               0x30
+#define   OCXL_DVSEC_TL_SEND_RATE               0x50
+#define OCXL_DVSEC_FUNC_ID                    0xF001
+#define   OCXL_DVSEC_FUNC_OFF_INDEX             0x08
+#define   OCXL_DVSEC_FUNC_OFF_ACTAG             0x0C
+#define OCXL_DVSEC_AFU_INFO_ID                0xF003
+#define   OCXL_DVSEC_AFU_INFO_AFU_IDX           0x0A
+#define   OCXL_DVSEC_AFU_INFO_OFF               0x0C
+#define   OCXL_DVSEC_AFU_INFO_DATA              0x10
+#define OCXL_DVSEC_AFU_CTRL_ID                0xF004
+#define   OCXL_DVSEC_AFU_CTRL_AFU_IDX           0x0A
+#define   OCXL_DVSEC_AFU_CTRL_TERM_PASID        0x0C
+#define   OCXL_DVSEC_AFU_CTRL_ENABLE            0x0F
+#define   OCXL_DVSEC_AFU_CTRL_PASID_SUP         0x10
+#define   OCXL_DVSEC_AFU_CTRL_PASID_EN          0x11
+#define   OCXL_DVSEC_AFU_CTRL_PASID_BASE        0x14
+#define   OCXL_DVSEC_AFU_CTRL_ACTAG_SUP         0x18
+#define   OCXL_DVSEC_AFU_CTRL_ACTAG_EN          0x1A
+#define   OCXL_DVSEC_AFU_CTRL_ACTAG_BASE        0x1C
+#define OCXL_DVSEC_VENDOR_ID                  0xF0F0
+#define   OCXL_DVSEC_VENDOR_CFG_VERS            0x0C
+#define   OCXL_DVSEC_VENDOR_TLX_VERS            0x10
+#define   OCXL_DVSEC_VENDOR_DLX_VERS            0x20
+#define   OCXL_DVSEC_VENDOR_RESET_RELOAD        0x38
+
+#endif /* _OCXL_CONFIG_H_ */