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, 386 insertions, 0 deletions

diff --git a/drivers/pinctrl/pinconf.c b/drivers/pinctrl/pinconf.c
new file mode 100644
index 000000000..81686844d
--- /dev/null
+++ b/drivers/pinctrl/pinconf.c
@@ -0,0 +1,386 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Core driver for the pin config portions of the pin control subsystem
+ *
+ * Copyright (C) 2011 ST-Ericsson SA
+ * Written on behalf of Linaro for ST-Ericsson
+ *
+ * Author: Linus Walleij <linus.walleij@linaro.org>
+ */
+#define pr_fmt(fmt) "pinconfig core: " fmt
+
+#include <linux/array_size.h>
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+
+#include <linux/pinctrl/machine.h>
+#include <linux/pinctrl/pinconf.h>
+#include <linux/pinctrl/pinctrl.h>
+
+#include "core.h"
+#include "pinconf.h"
+
+int pinconf_check_ops(struct pinctrl_dev *pctldev)
+{
+	const struct pinconf_ops *ops = pctldev->desc->confops;
+
+	/* We have to be able to config the pins in SOME way */
+	if (!ops->pin_config_set && !ops->pin_config_group_set) {
+		dev_err(pctldev->dev,
+			"pinconf has to be able to set a pins config\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+int pinconf_validate_map(const struct pinctrl_map *map, int i)
+{
+	if (!map->data.configs.group_or_pin) {
+		pr_err("failed to register map %s (%d): no group/pin given\n",
+		       map->name, i);
+		return -EINVAL;
+	}
+
+	if (!map->data.configs.num_configs ||
+			!map->data.configs.configs) {
+		pr_err("failed to register map %s (%d): no configs given\n",
+		       map->name, i);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int pin_config_get_for_pin(struct pinctrl_dev *pctldev, unsigned int pin,
+			   unsigned long *config)
+{
+	const struct pinconf_ops *ops = pctldev->desc->confops;
+
+	if (!ops || !ops->pin_config_get) {
+		dev_dbg(pctldev->dev,
+			"cannot get pin configuration, .pin_config_get missing in driver\n");
+		return -ENOTSUPP;
+	}
+
+	return ops->pin_config_get(pctldev, pin, config);
+}
+
+int pin_config_group_get(const char *dev_name, const char *pin_group,
+			 unsigned long *config)
+{
+	struct pinctrl_dev *pctldev;
+	const struct pinconf_ops *ops;
+	int selector, ret;
+
+	pctldev = get_pinctrl_dev_from_devname(dev_name);
+	if (!pctldev) {
+		ret = -EINVAL;
+		return ret;
+	}
+
+	mutex_lock(&pctldev->mutex);
+
+	ops = pctldev->desc->confops;
+
+	if (!ops || !ops->pin_config_group_get) {
+		dev_dbg(pctldev->dev,
+			"cannot get configuration for pin group, missing group config get function in driver\n");
+		ret = -ENOTSUPP;
+		goto unlock;
+	}
+
+	selector = pinctrl_get_group_selector(pctldev, pin_group);
+	if (selector < 0) {
+		ret = selector;
+		goto unlock;
+	}
+
+	ret = ops->pin_config_group_get(pctldev, selector, config);
+
+unlock:
+	mutex_unlock(&pctldev->mutex);
+	return ret;
+}
+
+int pinconf_map_to_setting(const struct pinctrl_map *map,
+			  struct pinctrl_setting *setting)
+{
+	struct pinctrl_dev *pctldev = setting->pctldev;
+	int pin;
+
+	switch (setting->type) {
+	case PIN_MAP_TYPE_CONFIGS_PIN:
+		pin = pin_get_from_name(pctldev,
+					map->data.configs.group_or_pin);
+		if (pin < 0) {
+			dev_err(pctldev->dev, "could not map pin config for \"%s\"",
+				map->data.configs.group_or_pin);
+			return pin;
+		}
+		setting->data.configs.group_or_pin = pin;
+		break;
+	case PIN_MAP_TYPE_CONFIGS_GROUP:
+		pin = pinctrl_get_group_selector(pctldev,
+					 map->data.configs.group_or_pin);
+		if (pin < 0) {
+			dev_err(pctldev->dev, "could not map group config for \"%s\"",
+				map->data.configs.group_or_pin);
+			return pin;
+		}
+		setting->data.configs.group_or_pin = pin;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	setting->data.configs.num_configs = map->data.configs.num_configs;
+	setting->data.configs.configs = map->data.configs.configs;
+
+	return 0;
+}
+
+void pinconf_free_setting(const struct pinctrl_setting *setting)
+{
+}
+
+int pinconf_apply_setting(const struct pinctrl_setting *setting)
+{
+	struct pinctrl_dev *pctldev = setting->pctldev;
+	const struct pinconf_ops *ops = pctldev->desc->confops;
+	int ret;
+
+	if (!ops) {
+		dev_err(pctldev->dev, "missing confops\n");
+		return -EINVAL;
+	}
+
+	switch (setting->type) {
+	case PIN_MAP_TYPE_CONFIGS_PIN:
+		if (!ops->pin_config_set) {
+			dev_err(pctldev->dev, "missing pin_config_set op\n");
+			return -EINVAL;
+		}
+		ret = ops->pin_config_set(pctldev,
+				setting->data.configs.group_or_pin,
+				setting->data.configs.configs,
+				setting->data.configs.num_configs);
+		if (ret < 0) {
+			dev_err(pctldev->dev,
+				"pin_config_set op failed for pin %d\n",
+				setting->data.configs.group_or_pin);
+			return ret;
+		}
+		break;
+	case PIN_MAP_TYPE_CONFIGS_GROUP:
+		if (!ops->pin_config_group_set) {
+			dev_err(pctldev->dev,
+				"missing pin_config_group_set op\n");
+			return -EINVAL;
+		}
+		ret = ops->pin_config_group_set(pctldev,
+				setting->data.configs.group_or_pin,
+				setting->data.configs.configs,
+				setting->data.configs.num_configs);
+		if (ret < 0) {
+			dev_err(pctldev->dev,
+				"pin_config_group_set op failed for group %d\n",
+				setting->data.configs.group_or_pin);
+			return ret;
+		}
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int pinconf_set_config(struct pinctrl_dev *pctldev, unsigned int pin,
+		       unsigned long *configs, size_t nconfigs)
+{
+	const struct pinconf_ops *ops;
+
+	ops = pctldev->desc->confops;
+	if (!ops || !ops->pin_config_set)
+		return -ENOTSUPP;
+
+	return ops->pin_config_set(pctldev, pin, configs, nconfigs);
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+static void pinconf_show_config(struct seq_file *s, struct pinctrl_dev *pctldev,
+				unsigned long *configs, unsigned int num_configs)
+{
+	const struct pinconf_ops *confops;
+	int i;
+
+	if (pctldev)
+		confops = pctldev->desc->confops;
+	else
+		confops = NULL;
+
+	for (i = 0; i < num_configs; i++) {
+		seq_puts(s, "config ");
+		if (confops && confops->pin_config_config_dbg_show)
+			confops->pin_config_config_dbg_show(pctldev, s,
+							    configs[i]);
+		else
+			seq_printf(s, "%08lx", configs[i]);
+		seq_putc(s, '\n');
+	}
+}
+
+void pinconf_show_map(struct seq_file *s, const struct pinctrl_map *map)
+{
+	struct pinctrl_dev *pctldev;
+
+	pctldev = get_pinctrl_dev_from_devname(map->ctrl_dev_name);
+
+	switch (map->type) {
+	case PIN_MAP_TYPE_CONFIGS_PIN:
+		seq_puts(s, "pin ");
+		break;
+	case PIN_MAP_TYPE_CONFIGS_GROUP:
+		seq_puts(s, "group ");
+		break;
+	default:
+		break;
+	}
+
+	seq_printf(s, "%s\n", map->data.configs.group_or_pin);
+
+	pinconf_show_config(s, pctldev, map->data.configs.configs,
+			    map->data.configs.num_configs);
+}
+
+void pinconf_show_setting(struct seq_file *s,
+			  const struct pinctrl_setting *setting)
+{
+	struct pinctrl_dev *pctldev = setting->pctldev;
+	const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
+	struct pin_desc *desc;
+
+	switch (setting->type) {
+	case PIN_MAP_TYPE_CONFIGS_PIN:
+		desc = pin_desc_get(setting->pctldev,
+				    setting->data.configs.group_or_pin);
+		seq_printf(s, "pin %s (%d)", desc->name,
+			   setting->data.configs.group_or_pin);
+		break;
+	case PIN_MAP_TYPE_CONFIGS_GROUP:
+		seq_printf(s, "group %s (%d)",
+			   pctlops->get_group_name(pctldev,
+						   setting->data.configs.group_or_pin),
+			   setting->data.configs.group_or_pin);
+		break;
+	default:
+		break;
+	}
+
+	/*
+	 * FIXME: We should really get the pin controller to dump the config
+	 * values, so they can be decoded to something meaningful.
+	 */
+	pinconf_show_config(s, pctldev, setting->data.configs.configs,
+			    setting->data.configs.num_configs);
+}
+
+static void pinconf_dump_pin(struct pinctrl_dev *pctldev,
+			     struct seq_file *s, int pin)
+{
+	const struct pinconf_ops *ops = pctldev->desc->confops;
+
+	/* no-op when not using generic pin config */
+	pinconf_generic_dump_pins(pctldev, s, NULL, pin);
+	if (ops && ops->pin_config_dbg_show)
+		ops->pin_config_dbg_show(pctldev, s, pin);
+}
+
+static int pinconf_pins_show(struct seq_file *s, void *what)
+{
+	struct pinctrl_dev *pctldev = s->private;
+	unsigned int i, pin;
+
+	seq_puts(s, "Pin config settings per pin\n");
+	seq_puts(s, "Format: pin (name): configs\n");
+
+	mutex_lock(&pctldev->mutex);
+
+	/* The pin number can be retrived from the pin controller descriptor */
+	for (i = 0; i < pctldev->desc->npins; i++) {
+		struct pin_desc *desc;
+
+		pin = pctldev->desc->pins[i].number;
+		desc = pin_desc_get(pctldev, pin);
+		/* Skip if we cannot search the pin */
+		if (!desc)
+			continue;
+
+		seq_printf(s, "pin %d (%s): ", pin, desc->name);
+
+		pinconf_dump_pin(pctldev, s, pin);
+		seq_putc(s, '\n');
+	}
+
+	mutex_unlock(&pctldev->mutex);
+
+	return 0;
+}
+
+static void pinconf_dump_group(struct pinctrl_dev *pctldev,
+			       struct seq_file *s, unsigned int selector,
+			       const char *gname)
+{
+	const struct pinconf_ops *ops = pctldev->desc->confops;
+
+	/* no-op when not using generic pin config */
+	pinconf_generic_dump_pins(pctldev, s, gname, 0);
+	if (ops && ops->pin_config_group_dbg_show)
+		ops->pin_config_group_dbg_show(pctldev, s, selector);
+}
+
+static int pinconf_groups_show(struct seq_file *s, void *what)
+{
+	struct pinctrl_dev *pctldev = s->private;
+	const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
+	unsigned int selector = 0;
+	unsigned int ngroups;
+
+	if (!pctlops->get_groups_count || !pctlops->get_group_name)
+		return 0;
+
+	ngroups = pctlops->get_groups_count(pctldev);
+
+	seq_puts(s, "Pin config settings per pin group\n");
+	seq_puts(s, "Format: group (name): configs\n");
+
+	while (selector < ngroups) {
+		const char *gname = pctlops->get_group_name(pctldev, selector);
+
+		seq_printf(s, "%u (%s): ", selector, gname);
+		pinconf_dump_group(pctldev, s, selector, gname);
+		seq_putc(s, '\n');
+		selector++;
+	}
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(pinconf_pins);
+DEFINE_SHOW_ATTRIBUTE(pinconf_groups);
+
+void pinconf_init_device_debugfs(struct dentry *devroot,
+			 struct pinctrl_dev *pctldev)
+{
+	debugfs_create_file("pinconf-pins", 0444,
+			    devroot, pctldev, &pinconf_pins_fops);
+	debugfs_create_file("pinconf-groups", 0444,
+			    devroot, pctldev, &pinconf_groups_fops);
+}
+
+#endif