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, 259 insertions, 0 deletions

diff --git a/drivers/crypto/ccp/dbc.c b/drivers/crypto/ccp/dbc.c
new file mode 100644
index 000000000..410084a90
--- /dev/null
+++ b/drivers/crypto/ccp/dbc.c
@@ -0,0 +1,259 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AMD Secure Processor Dynamic Boost Control interface
+ *
+ * Copyright (C) 2023 Advanced Micro Devices, Inc.
+ *
+ * Author: Mario Limonciello <mario.limonciello@amd.com>
+ */
+
+#include <linux/mutex.h>
+
+#include "dbc.h"
+
+#define DBC_DEFAULT_TIMEOUT		(10 * MSEC_PER_SEC)
+struct error_map {
+	u32 psp;
+	int ret;
+};
+
+#define DBC_ERROR_ACCESS_DENIED		0x0001
+#define DBC_ERROR_EXCESS_DATA		0x0004
+#define DBC_ERROR_BAD_PARAMETERS	0x0006
+#define DBC_ERROR_BAD_STATE		0x0007
+#define DBC_ERROR_NOT_IMPLEMENTED	0x0009
+#define DBC_ERROR_BUSY			0x000D
+#define DBC_ERROR_MESSAGE_FAILURE	0x0307
+#define DBC_ERROR_OVERFLOW		0x300F
+#define DBC_ERROR_SIGNATURE_INVALID	0x3072
+
+static struct error_map error_codes[] = {
+	{DBC_ERROR_ACCESS_DENIED,	-EACCES},
+	{DBC_ERROR_EXCESS_DATA,		-E2BIG},
+	{DBC_ERROR_BAD_PARAMETERS,	-EINVAL},
+	{DBC_ERROR_BAD_STATE,		-EAGAIN},
+	{DBC_ERROR_MESSAGE_FAILURE,	-ENOENT},
+	{DBC_ERROR_NOT_IMPLEMENTED,	-ENOENT},
+	{DBC_ERROR_BUSY,		-EBUSY},
+	{DBC_ERROR_OVERFLOW,		-ENFILE},
+	{DBC_ERROR_SIGNATURE_INVALID,	-EPERM},
+	{0x0,	0x0},
+};
+
+static inline int send_dbc_cmd_thru_ext(struct psp_dbc_device *dbc_dev, int msg)
+{
+	dbc_dev->mbox->ext_req.header.sub_cmd_id = msg;
+
+	return psp_extended_mailbox_cmd(dbc_dev->psp,
+					DBC_DEFAULT_TIMEOUT,
+					(struct psp_ext_request *)dbc_dev->mbox);
+}
+
+static inline int send_dbc_cmd_thru_pa(struct psp_dbc_device *dbc_dev, int msg)
+{
+	return psp_send_platform_access_msg(msg,
+					    (struct psp_request *)dbc_dev->mbox);
+}
+
+static int send_dbc_cmd(struct psp_dbc_device *dbc_dev, int msg)
+{
+	int ret;
+
+	*dbc_dev->result = 0;
+	ret = dbc_dev->use_ext ? send_dbc_cmd_thru_ext(dbc_dev, msg) :
+				 send_dbc_cmd_thru_pa(dbc_dev, msg);
+	if (ret == -EIO) {
+		int i;
+
+		dev_dbg(dbc_dev->dev,
+			 "msg 0x%x failed with PSP error: 0x%x\n",
+			 msg, *dbc_dev->result);
+
+		for (i = 0; error_codes[i].psp; i++) {
+			if (*dbc_dev->result == error_codes[i].psp)
+				return error_codes[i].ret;
+		}
+	}
+
+	return ret;
+}
+
+static int send_dbc_nonce(struct psp_dbc_device *dbc_dev)
+{
+	int ret;
+
+	*dbc_dev->payload_size = dbc_dev->header_size + sizeof(struct dbc_user_nonce);
+	ret = send_dbc_cmd(dbc_dev, PSP_DYNAMIC_BOOST_GET_NONCE);
+	if (ret == -EAGAIN) {
+		dev_dbg(dbc_dev->dev, "retrying get nonce\n");
+		ret = send_dbc_cmd(dbc_dev, PSP_DYNAMIC_BOOST_GET_NONCE);
+	}
+
+	return ret;
+}
+
+static int send_dbc_parameter(struct psp_dbc_device *dbc_dev)
+{
+	struct dbc_user_param *user_param = (struct dbc_user_param *)dbc_dev->payload;
+
+	switch (user_param->msg_index) {
+	case PARAM_SET_FMAX_CAP:
+	case PARAM_SET_PWR_CAP:
+	case PARAM_SET_GFX_MODE:
+		return send_dbc_cmd(dbc_dev, PSP_DYNAMIC_BOOST_SET_PARAMETER);
+	case PARAM_GET_FMAX_CAP:
+	case PARAM_GET_PWR_CAP:
+	case PARAM_GET_CURR_TEMP:
+	case PARAM_GET_FMAX_MAX:
+	case PARAM_GET_FMAX_MIN:
+	case PARAM_GET_SOC_PWR_MAX:
+	case PARAM_GET_SOC_PWR_MIN:
+	case PARAM_GET_SOC_PWR_CUR:
+	case PARAM_GET_GFX_MODE:
+		return send_dbc_cmd(dbc_dev, PSP_DYNAMIC_BOOST_GET_PARAMETER);
+	}
+
+	return -EINVAL;
+}
+
+void dbc_dev_destroy(struct psp_device *psp)
+{
+	struct psp_dbc_device *dbc_dev = psp->dbc_data;
+
+	if (!dbc_dev)
+		return;
+
+	misc_deregister(&dbc_dev->char_dev);
+	mutex_destroy(&dbc_dev->ioctl_mutex);
+	psp->dbc_data = NULL;
+}
+
+static long dbc_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct psp_device *psp_master = psp_get_master_device();
+	void __user *argp = (void __user *)arg;
+	struct psp_dbc_device *dbc_dev;
+	int ret;
+
+	if (!psp_master || !psp_master->dbc_data)
+		return -ENODEV;
+	dbc_dev = psp_master->dbc_data;
+
+	guard(mutex)(&dbc_dev->ioctl_mutex);
+
+	switch (cmd) {
+	case DBCIOCNONCE:
+		if (copy_from_user(dbc_dev->payload, argp, sizeof(struct dbc_user_nonce)))
+			return -EFAULT;
+
+		ret = send_dbc_nonce(dbc_dev);
+		if (ret)
+			return ret;
+
+		if (copy_to_user(argp, dbc_dev->payload, sizeof(struct dbc_user_nonce)))
+			return -EFAULT;
+		break;
+	case DBCIOCUID:
+		if (copy_from_user(dbc_dev->payload, argp, sizeof(struct dbc_user_setuid)))
+			return -EFAULT;
+
+		*dbc_dev->payload_size = dbc_dev->header_size + sizeof(struct dbc_user_setuid);
+		ret = send_dbc_cmd(dbc_dev, PSP_DYNAMIC_BOOST_SET_UID);
+		if (ret)
+			return ret;
+
+		if (copy_to_user(argp, dbc_dev->payload, sizeof(struct dbc_user_setuid)))
+			return -EFAULT;
+		break;
+	case DBCIOCPARAM:
+		if (copy_from_user(dbc_dev->payload, argp, sizeof(struct dbc_user_param)))
+			return -EFAULT;
+
+		*dbc_dev->payload_size = dbc_dev->header_size + sizeof(struct dbc_user_param);
+		ret = send_dbc_parameter(dbc_dev);
+		if (ret)
+			return ret;
+
+		if (copy_to_user(argp, dbc_dev->payload, sizeof(struct dbc_user_param)))
+			return -EFAULT;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct file_operations dbc_fops = {
+	.owner	= THIS_MODULE,
+	.unlocked_ioctl = dbc_ioctl,
+};
+
+int dbc_dev_init(struct psp_device *psp)
+{
+	struct device *dev = psp->dev;
+	struct psp_dbc_device *dbc_dev;
+	int ret;
+
+	dbc_dev = devm_kzalloc(dev, sizeof(*dbc_dev), GFP_KERNEL);
+	if (!dbc_dev)
+		return -ENOMEM;
+
+	BUILD_BUG_ON(sizeof(union dbc_buffer) > PAGE_SIZE);
+	dbc_dev->mbox = (void *)devm_get_free_pages(dev, GFP_KERNEL | __GFP_ZERO, 0);
+	if (!dbc_dev->mbox) {
+		ret = -ENOMEM;
+		goto cleanup_dev;
+	}
+
+	psp->dbc_data = dbc_dev;
+	dbc_dev->dev = dev;
+	dbc_dev->psp = psp;
+
+	if (psp->capability.dbc_thru_ext) {
+		dbc_dev->use_ext = true;
+		dbc_dev->payload_size = &dbc_dev->mbox->ext_req.header.payload_size;
+		dbc_dev->result = &dbc_dev->mbox->ext_req.header.status;
+		dbc_dev->payload = &dbc_dev->mbox->ext_req.buf;
+		dbc_dev->header_size = sizeof(struct psp_ext_req_buffer_hdr);
+	} else {
+		dbc_dev->payload_size = &dbc_dev->mbox->pa_req.header.payload_size;
+		dbc_dev->result = &dbc_dev->mbox->pa_req.header.status;
+		dbc_dev->payload = &dbc_dev->mbox->pa_req.buf;
+		dbc_dev->header_size = sizeof(struct psp_req_buffer_hdr);
+	}
+
+	ret = send_dbc_nonce(dbc_dev);
+	if (ret == -EACCES) {
+		dev_dbg(dbc_dev->dev,
+			"dynamic boost control was previously authenticated\n");
+		ret = 0;
+	}
+	dev_dbg(dbc_dev->dev, "dynamic boost control is %savailable\n",
+		ret ? "un" : "");
+	if (ret) {
+		ret = 0;
+		goto cleanup_mbox;
+	}
+
+	dbc_dev->char_dev.minor = MISC_DYNAMIC_MINOR;
+	dbc_dev->char_dev.name = "dbc";
+	dbc_dev->char_dev.fops = &dbc_fops;
+	dbc_dev->char_dev.mode = 0600;
+	ret = misc_register(&dbc_dev->char_dev);
+	if (ret)
+		goto cleanup_mbox;
+
+	mutex_init(&dbc_dev->ioctl_mutex);
+
+	return 0;
+
+cleanup_mbox:
+	devm_free_pages(dev, (unsigned long)dbc_dev->mbox);
+
+cleanup_dev:
+	psp->dbc_data = NULL;
+	devm_kfree(dev, dbc_dev);
+
+	return ret;
+}