x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

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);