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, 137 insertions, 0 deletions

diff --git a/drivers/firmware/imx/misc.c b/drivers/firmware/imx/misc.c
new file mode 100644
index 000000000..d073cb3ce
--- /dev/null
+++ b/drivers/firmware/imx/misc.c
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ * Copyright 2017~2018 NXP
+ *  Author: Dong Aisheng <aisheng.dong@nxp.com>
+ *
+ * File containing client-side RPC functions for the MISC service. These
+ * function are ported to clients that communicate to the SC.
+ *
+ */
+
+#include <linux/firmware/imx/svc/misc.h>
+
+struct imx_sc_msg_req_misc_set_ctrl {
+	struct imx_sc_rpc_msg hdr;
+	u32 ctrl;
+	u32 val;
+	u16 resource;
+} __packed __aligned(4);
+
+struct imx_sc_msg_req_cpu_start {
+	struct imx_sc_rpc_msg hdr;
+	u32 address_hi;
+	u32 address_lo;
+	u16 resource;
+	u8 enable;
+} __packed __aligned(4);
+
+struct imx_sc_msg_req_misc_get_ctrl {
+	struct imx_sc_rpc_msg hdr;
+	u32 ctrl;
+	u16 resource;
+} __packed __aligned(4);
+
+struct imx_sc_msg_resp_misc_get_ctrl {
+	struct imx_sc_rpc_msg hdr;
+	u32 val;
+} __packed __aligned(4);
+
+/*
+ * This function sets a miscellaneous control value.
+ *
+ * @param[in]     ipc         IPC handle
+ * @param[in]     resource    resource the control is associated with
+ * @param[in]     ctrl        control to change
+ * @param[in]     val         value to apply to the control
+ *
+ * @return Returns 0 for success and < 0 for errors.
+ */
+
+int imx_sc_misc_set_control(struct imx_sc_ipc *ipc, u32 resource,
+			    u8 ctrl, u32 val)
+{
+	struct imx_sc_msg_req_misc_set_ctrl msg;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+
+	hdr->ver = IMX_SC_RPC_VERSION;
+	hdr->svc = (uint8_t)IMX_SC_RPC_SVC_MISC;
+	hdr->func = (uint8_t)IMX_SC_MISC_FUNC_SET_CONTROL;
+	hdr->size = 4;
+
+	msg.ctrl = ctrl;
+	msg.val = val;
+	msg.resource = resource;
+
+	return imx_scu_call_rpc(ipc, &msg, true);
+}
+EXPORT_SYMBOL(imx_sc_misc_set_control);
+
+/*
+ * This function gets a miscellaneous control value.
+ *
+ * @param[in]     ipc         IPC handle
+ * @param[in]     resource    resource the control is associated with
+ * @param[in]     ctrl        control to get
+ * @param[out]    val         pointer to return the control value
+ *
+ * @return Returns 0 for success and < 0 for errors.
+ */
+
+int imx_sc_misc_get_control(struct imx_sc_ipc *ipc, u32 resource,
+			    u8 ctrl, u32 *val)
+{
+	struct imx_sc_msg_req_misc_get_ctrl msg;
+	struct imx_sc_msg_resp_misc_get_ctrl *resp;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+	int ret;
+
+	hdr->ver = IMX_SC_RPC_VERSION;
+	hdr->svc = (uint8_t)IMX_SC_RPC_SVC_MISC;
+	hdr->func = (uint8_t)IMX_SC_MISC_FUNC_GET_CONTROL;
+	hdr->size = 3;
+
+	msg.ctrl = ctrl;
+	msg.resource = resource;
+
+	ret = imx_scu_call_rpc(ipc, &msg, true);
+	if (ret)
+		return ret;
+
+	resp = (struct imx_sc_msg_resp_misc_get_ctrl *)&msg;
+	if (val != NULL)
+		*val = resp->val;
+
+	return 0;
+}
+EXPORT_SYMBOL(imx_sc_misc_get_control);
+
+/*
+ * This function starts/stops a CPU identified by @resource
+ *
+ * @param[in]     ipc         IPC handle
+ * @param[in]     resource    resource the control is associated with
+ * @param[in]     enable      true for start, false for stop
+ * @param[in]     phys_addr   initial instruction address to be executed
+ *
+ * @return Returns 0 for success and < 0 for errors.
+ */
+int imx_sc_pm_cpu_start(struct imx_sc_ipc *ipc, u32 resource,
+			bool enable, u64 phys_addr)
+{
+	struct imx_sc_msg_req_cpu_start msg;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+
+	hdr->ver = IMX_SC_RPC_VERSION;
+	hdr->svc = IMX_SC_RPC_SVC_PM;
+	hdr->func = IMX_SC_PM_FUNC_CPU_START;
+	hdr->size = 4;
+
+	msg.address_hi = phys_addr >> 32;
+	msg.address_lo = phys_addr;
+	msg.resource = resource;
+	msg.enable = enable;
+
+	return imx_scu_call_rpc(ipc, &msg, true);
+}
+EXPORT_SYMBOL(imx_sc_pm_cpu_start);