From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions 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) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- drivers/rtc/rtc-hid-sensor-time.c | 329 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 329 insertions(+) create mode 100644 drivers/rtc/rtc-hid-sensor-time.c (limited to 'drivers/rtc/rtc-hid-sensor-time.c') diff --git a/drivers/rtc/rtc-hid-sensor-time.c b/drivers/rtc/rtc-hid-sensor-time.c new file mode 100644 index 000000000..6228d0b24 --- /dev/null +++ b/drivers/rtc/rtc-hid-sensor-time.c @@ -0,0 +1,329 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * HID Sensor Time Driver + * Copyright (c) 2012, Alexander Holler. + */ +#include +#include +#include +#include +#include +#include + +enum hid_time_channel { + CHANNEL_SCAN_INDEX_YEAR, + CHANNEL_SCAN_INDEX_MONTH, + CHANNEL_SCAN_INDEX_DAY, + CHANNEL_SCAN_INDEX_HOUR, + CHANNEL_SCAN_INDEX_MINUTE, + CHANNEL_SCAN_INDEX_SECOND, + TIME_RTC_CHANNEL_MAX, +}; + +struct hid_time_state { + struct hid_sensor_hub_callbacks callbacks; + struct hid_sensor_common common_attributes; + struct hid_sensor_hub_attribute_info info[TIME_RTC_CHANNEL_MAX]; + struct rtc_time last_time; + spinlock_t lock_last_time; + struct completion comp_last_time; + struct rtc_time time_buf; + struct rtc_device *rtc; +}; + +static const u32 hid_time_addresses[TIME_RTC_CHANNEL_MAX] = { + HID_USAGE_SENSOR_TIME_YEAR, + HID_USAGE_SENSOR_TIME_MONTH, + HID_USAGE_SENSOR_TIME_DAY, + HID_USAGE_SENSOR_TIME_HOUR, + HID_USAGE_SENSOR_TIME_MINUTE, + HID_USAGE_SENSOR_TIME_SECOND, +}; + +/* Channel names for verbose error messages */ +static const char * const hid_time_channel_names[TIME_RTC_CHANNEL_MAX] = { + "year", "month", "day", "hour", "minute", "second", +}; + +/* Callback handler to send event after all samples are received and captured */ +static int hid_time_proc_event(struct hid_sensor_hub_device *hsdev, + unsigned usage_id, void *priv) +{ + unsigned long flags; + struct hid_time_state *time_state = platform_get_drvdata(priv); + + spin_lock_irqsave(&time_state->lock_last_time, flags); + time_state->last_time = time_state->time_buf; + spin_unlock_irqrestore(&time_state->lock_last_time, flags); + complete(&time_state->comp_last_time); + return 0; +} + +static u32 hid_time_value(size_t raw_len, char *raw_data) +{ + switch (raw_len) { + case 1: + return *(u8 *)raw_data; + case 2: + return *(u16 *)raw_data; + case 4: + return *(u32 *)raw_data; + default: + return (u32)(~0U); /* 0xff... or -1 to denote an error */ + } +} + +static int hid_time_capture_sample(struct hid_sensor_hub_device *hsdev, + unsigned usage_id, size_t raw_len, + char *raw_data, void *priv) +{ + struct hid_time_state *time_state = platform_get_drvdata(priv); + struct rtc_time *time_buf = &time_state->time_buf; + + switch (usage_id) { + case HID_USAGE_SENSOR_TIME_YEAR: + /* + * The draft for HID-sensors (HUTRR39) currently doesn't define + * the range for the year attribute. Therefor we support + * 8 bit (0-99) and 16 or 32 bits (full) as size for the year. + */ + if (raw_len == 1) { + time_buf->tm_year = *(u8 *)raw_data; + if (time_buf->tm_year < 70) + /* assume we are in 1970...2069 */ + time_buf->tm_year += 100; + } else + time_buf->tm_year = + (int)hid_time_value(raw_len, raw_data)-1900; + break; + case HID_USAGE_SENSOR_TIME_MONTH: + /* sensors are sending the month as 1-12, we need 0-11 */ + time_buf->tm_mon = (int)hid_time_value(raw_len, raw_data)-1; + break; + case HID_USAGE_SENSOR_TIME_DAY: + time_buf->tm_mday = (int)hid_time_value(raw_len, raw_data); + break; + case HID_USAGE_SENSOR_TIME_HOUR: + time_buf->tm_hour = (int)hid_time_value(raw_len, raw_data); + break; + case HID_USAGE_SENSOR_TIME_MINUTE: + time_buf->tm_min = (int)hid_time_value(raw_len, raw_data); + break; + case HID_USAGE_SENSOR_TIME_SECOND: + time_buf->tm_sec = (int)hid_time_value(raw_len, raw_data); + break; + default: + return -EINVAL; + } + return 0; +} + +/* small helper, haven't found any other way */ +static const char *hid_time_attrib_name(u32 attrib_id) +{ + static const char unknown[] = "unknown"; + unsigned i; + + for (i = 0; i < TIME_RTC_CHANNEL_MAX; ++i) { + if (hid_time_addresses[i] == attrib_id) + return hid_time_channel_names[i]; + } + return unknown; /* should never happen */ +} + +static int hid_time_parse_report(struct platform_device *pdev, + struct hid_sensor_hub_device *hsdev, + unsigned usage_id, + struct hid_time_state *time_state) +{ + int report_id, i; + + for (i = 0; i < TIME_RTC_CHANNEL_MAX; ++i) + if (sensor_hub_input_get_attribute_info(hsdev, + HID_INPUT_REPORT, usage_id, + hid_time_addresses[i], + &time_state->info[i]) < 0) + return -EINVAL; + /* Check the (needed) attributes for sanity */ + report_id = time_state->info[0].report_id; + if (report_id < 0) { + dev_err(&pdev->dev, "bad report ID!\n"); + return -EINVAL; + } + for (i = 0; i < TIME_RTC_CHANNEL_MAX; ++i) { + if (time_state->info[i].report_id != report_id) { + dev_err(&pdev->dev, + "not all needed attributes inside the same report!\n"); + return -EINVAL; + } + if (time_state->info[i].size == 3 || + time_state->info[i].size > 4) { + dev_err(&pdev->dev, + "attribute '%s' not 8, 16 or 32 bits wide!\n", + hid_time_attrib_name( + time_state->info[i].attrib_id)); + return -EINVAL; + } + if (time_state->info[i].units != + HID_USAGE_SENSOR_UNITS_NOT_SPECIFIED && + /* allow attribute seconds with unit seconds */ + !(time_state->info[i].attrib_id == + HID_USAGE_SENSOR_TIME_SECOND && + time_state->info[i].units == + HID_USAGE_SENSOR_UNITS_SECOND)) { + dev_err(&pdev->dev, + "attribute '%s' hasn't a unit of type 'none'!\n", + hid_time_attrib_name( + time_state->info[i].attrib_id)); + return -EINVAL; + } + if (time_state->info[i].unit_expo) { + dev_err(&pdev->dev, + "attribute '%s' hasn't a unit exponent of 1!\n", + hid_time_attrib_name( + time_state->info[i].attrib_id)); + return -EINVAL; + } + } + + return 0; +} + +static int hid_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + unsigned long flags; + struct hid_time_state *time_state = dev_get_drvdata(dev); + int ret; + + reinit_completion(&time_state->comp_last_time); + /* get a report with all values through requesting one value */ + sensor_hub_input_attr_get_raw_value(time_state->common_attributes.hsdev, + HID_USAGE_SENSOR_TIME, hid_time_addresses[0], + time_state->info[0].report_id, SENSOR_HUB_SYNC, false); + /* wait for all values (event) */ + ret = wait_for_completion_killable_timeout( + &time_state->comp_last_time, HZ*6); + if (ret > 0) { + /* no error */ + spin_lock_irqsave(&time_state->lock_last_time, flags); + *tm = time_state->last_time; + spin_unlock_irqrestore(&time_state->lock_last_time, flags); + return 0; + } + if (!ret) + return -EIO; /* timeouted */ + return ret; /* killed (-ERESTARTSYS) */ +} + +static const struct rtc_class_ops hid_time_rtc_ops = { + .read_time = hid_rtc_read_time, +}; + +static int hid_time_probe(struct platform_device *pdev) +{ + int ret = 0; + struct hid_sensor_hub_device *hsdev = dev_get_platdata(&pdev->dev); + struct hid_time_state *time_state = devm_kzalloc(&pdev->dev, + sizeof(struct hid_time_state), GFP_KERNEL); + + if (time_state == NULL) + return -ENOMEM; + + platform_set_drvdata(pdev, time_state); + + spin_lock_init(&time_state->lock_last_time); + init_completion(&time_state->comp_last_time); + time_state->common_attributes.hsdev = hsdev; + time_state->common_attributes.pdev = pdev; + + ret = hid_sensor_parse_common_attributes(hsdev, + HID_USAGE_SENSOR_TIME, + &time_state->common_attributes, + NULL, + 0); + if (ret) { + dev_err(&pdev->dev, "failed to setup common attributes!\n"); + return ret; + } + + ret = hid_time_parse_report(pdev, hsdev, HID_USAGE_SENSOR_TIME, + time_state); + if (ret) { + dev_err(&pdev->dev, "failed to setup attributes!\n"); + return ret; + } + + time_state->callbacks.send_event = hid_time_proc_event; + time_state->callbacks.capture_sample = hid_time_capture_sample; + time_state->callbacks.pdev = pdev; + ret = sensor_hub_register_callback(hsdev, HID_USAGE_SENSOR_TIME, + &time_state->callbacks); + if (ret < 0) { + dev_err(&pdev->dev, "register callback failed!\n"); + return ret; + } + + ret = sensor_hub_device_open(hsdev); + if (ret) { + dev_err(&pdev->dev, "failed to open sensor hub device!\n"); + goto err_open; + } + + /* + * Enable HID input processing early in order to be able to read the + * clock already in devm_rtc_device_register(). + */ + hid_device_io_start(hsdev->hdev); + + time_state->rtc = devm_rtc_device_register(&pdev->dev, + "hid-sensor-time", &hid_time_rtc_ops, + THIS_MODULE); + + if (IS_ERR(time_state->rtc)) { + hid_device_io_stop(hsdev->hdev); + ret = PTR_ERR(time_state->rtc); + time_state->rtc = NULL; + dev_err(&pdev->dev, "rtc device register failed!\n"); + goto err_rtc; + } + + return ret; + +err_rtc: + sensor_hub_device_close(hsdev); +err_open: + sensor_hub_remove_callback(hsdev, HID_USAGE_SENSOR_TIME); + return ret; +} + +static void hid_time_remove(struct platform_device *pdev) +{ + struct hid_sensor_hub_device *hsdev = dev_get_platdata(&pdev->dev); + + sensor_hub_device_close(hsdev); + sensor_hub_remove_callback(hsdev, HID_USAGE_SENSOR_TIME); +} + +static const struct platform_device_id hid_time_ids[] = { + { + /* Format: HID-SENSOR-usage_id_in_hex_lowercase */ + .name = "HID-SENSOR-2000a0", + }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(platform, hid_time_ids); + +static struct platform_driver hid_time_platform_driver = { + .id_table = hid_time_ids, + .driver = { + .name = KBUILD_MODNAME, + }, + .probe = hid_time_probe, + .remove = hid_time_remove, +}; +module_platform_driver(hid_time_platform_driver); + +MODULE_DESCRIPTION("HID Sensor Time"); +MODULE_AUTHOR("Alexander Holler "); +MODULE_LICENSE("GPL"); +MODULE_IMPORT_NS("IIO_HID"); -- cgit v1.3.1