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/input/keyboard/sunkbd.c | 376 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 376 insertions(+) create mode 100644 drivers/input/keyboard/sunkbd.c (limited to 'drivers/input/keyboard/sunkbd.c') diff --git a/drivers/input/keyboard/sunkbd.c b/drivers/input/keyboard/sunkbd.c new file mode 100644 index 000000000..5a0020827 --- /dev/null +++ b/drivers/input/keyboard/sunkbd.c @@ -0,0 +1,376 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 1999-2001 Vojtech Pavlik + */ + +/* + * Sun keyboard driver for Linux + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#define DRIVER_DESC "Sun keyboard driver" + +MODULE_AUTHOR("Vojtech Pavlik "); +MODULE_DESCRIPTION(DRIVER_DESC); +MODULE_LICENSE("GPL"); + +static unsigned char sunkbd_keycode[128] = { + 0,128,114,129,115, 59, 60, 68, 61, 87, 62, 88, 63,100, 64,112, + 65, 66, 67, 56,103,119, 99, 70,105,130,131,108,106, 1, 2, 3, + 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 41, 14,110,113, 98, 55, + 116,132, 83,133,102, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, + 26, 27,111,127, 71, 72, 73, 74,134,135,107, 0, 29, 30, 31, 32, + 33, 34, 35, 36, 37, 38, 39, 40, 43, 28, 96, 75, 76, 77, 82,136, + 104,137, 69, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54,101, + 79, 80, 81, 0, 0, 0,138, 58,125, 57,126,109, 86, 78 +}; + +#define SUNKBD_CMD_RESET 0x1 +#define SUNKBD_CMD_BELLON 0x2 +#define SUNKBD_CMD_BELLOFF 0x3 +#define SUNKBD_CMD_CLICK 0xa +#define SUNKBD_CMD_NOCLICK 0xb +#define SUNKBD_CMD_SETLED 0xe +#define SUNKBD_CMD_LAYOUT 0xf + +#define SUNKBD_RET_RESET 0xff +#define SUNKBD_RET_ALLUP 0x7f +#define SUNKBD_RET_LAYOUT 0xfe + +#define SUNKBD_LAYOUT_5_MASK 0x20 +#define SUNKBD_RELEASE 0x80 +#define SUNKBD_KEY 0x7f + +/* + * Per-keyboard data. + */ + +struct sunkbd { + unsigned char keycode[ARRAY_SIZE(sunkbd_keycode)]; + struct input_dev *dev; + struct serio *serio; + struct work_struct tq; + wait_queue_head_t wait; + char name[64]; + char phys[32]; + char type; + bool enabled; + volatile s8 reset; + volatile s8 layout; +}; + +/* + * sunkbd_interrupt() is called by the low level driver when a character + * is received. + */ + +static irqreturn_t sunkbd_interrupt(struct serio *serio, + unsigned char data, unsigned int flags) +{ + struct sunkbd *sunkbd = serio_get_drvdata(serio); + + if (sunkbd->reset <= -1) { + /* + * If cp[i] is 0xff, sunkbd->reset will stay -1. + * The keyboard sends 0xff 0xff 0xID on powerup. + */ + sunkbd->reset = data; + wake_up_interruptible(&sunkbd->wait); + goto out; + } + + if (sunkbd->layout == -1) { + sunkbd->layout = data; + wake_up_interruptible(&sunkbd->wait); + goto out; + } + + switch (data) { + + case SUNKBD_RET_RESET: + if (sunkbd->enabled) + schedule_work(&sunkbd->tq); + sunkbd->reset = -1; + break; + + case SUNKBD_RET_LAYOUT: + sunkbd->layout = -1; + break; + + case SUNKBD_RET_ALLUP: /* All keys released */ + break; + + default: + if (!sunkbd->enabled) + break; + + if (sunkbd->keycode[data & SUNKBD_KEY]) { + input_report_key(sunkbd->dev, + sunkbd->keycode[data & SUNKBD_KEY], + !(data & SUNKBD_RELEASE)); + input_sync(sunkbd->dev); + } else { + printk(KERN_WARNING + "sunkbd.c: Unknown key (scancode %#x) %s.\n", + data & SUNKBD_KEY, + data & SUNKBD_RELEASE ? "released" : "pressed"); + } + } +out: + return IRQ_HANDLED; +} + +/* + * sunkbd_event() handles events from the input module. + */ + +static int sunkbd_event(struct input_dev *dev, + unsigned int type, unsigned int code, int value) +{ + struct sunkbd *sunkbd = input_get_drvdata(dev); + + switch (type) { + + case EV_LED: + + serio_write(sunkbd->serio, SUNKBD_CMD_SETLED); + serio_write(sunkbd->serio, + (!!test_bit(LED_CAPSL, dev->led) << 3) | + (!!test_bit(LED_SCROLLL, dev->led) << 2) | + (!!test_bit(LED_COMPOSE, dev->led) << 1) | + !!test_bit(LED_NUML, dev->led)); + return 0; + + case EV_SND: + + switch (code) { + + case SND_CLICK: + serio_write(sunkbd->serio, SUNKBD_CMD_NOCLICK - value); + return 0; + + case SND_BELL: + serio_write(sunkbd->serio, SUNKBD_CMD_BELLOFF - value); + return 0; + } + + break; + } + + return -1; +} + +/* + * sunkbd_initialize() checks for a Sun keyboard attached, and determines + * its type. + */ + +static int sunkbd_initialize(struct sunkbd *sunkbd) +{ + sunkbd->reset = -2; + serio_write(sunkbd->serio, SUNKBD_CMD_RESET); + wait_event_interruptible_timeout(sunkbd->wait, sunkbd->reset >= 0, HZ); + if (sunkbd->reset < 0) + return -1; + + sunkbd->type = sunkbd->reset; + + if (sunkbd->type == 4) { /* Type 4 keyboard */ + sunkbd->layout = -2; + serio_write(sunkbd->serio, SUNKBD_CMD_LAYOUT); + wait_event_interruptible_timeout(sunkbd->wait, + sunkbd->layout >= 0, HZ / 4); + if (sunkbd->layout < 0) + return -1; + if (sunkbd->layout & SUNKBD_LAYOUT_5_MASK) + sunkbd->type = 5; + } + + return 0; +} + +/* + * sunkbd_set_leds_beeps() sets leds and beeps to a state the computer remembers + * they were in. + */ + +static void sunkbd_set_leds_beeps(struct sunkbd *sunkbd) +{ + serio_write(sunkbd->serio, SUNKBD_CMD_SETLED); + serio_write(sunkbd->serio, + (!!test_bit(LED_CAPSL, sunkbd->dev->led) << 3) | + (!!test_bit(LED_SCROLLL, sunkbd->dev->led) << 2) | + (!!test_bit(LED_COMPOSE, sunkbd->dev->led) << 1) | + !!test_bit(LED_NUML, sunkbd->dev->led)); + serio_write(sunkbd->serio, + SUNKBD_CMD_NOCLICK - !!test_bit(SND_CLICK, sunkbd->dev->snd)); + serio_write(sunkbd->serio, + SUNKBD_CMD_BELLOFF - !!test_bit(SND_BELL, sunkbd->dev->snd)); +} + + +/* + * sunkbd_reinit() wait for the keyboard reset to complete and restores state + * of leds and beeps. + */ + +static void sunkbd_reinit(struct work_struct *work) +{ + struct sunkbd *sunkbd = container_of(work, struct sunkbd, tq); + + /* + * It is OK that we check sunkbd->enabled without pausing serio, + * as we only want to catch true->false transition that will + * happen once and we will be woken up for it. + */ + wait_event_interruptible_timeout(sunkbd->wait, + sunkbd->reset >= 0 || !sunkbd->enabled, + HZ); + + if (sunkbd->reset >= 0 && sunkbd->enabled) + sunkbd_set_leds_beeps(sunkbd); +} + +static void sunkbd_enable(struct sunkbd *sunkbd, bool enable) +{ + scoped_guard(serio_pause_rx, sunkbd->serio) + sunkbd->enabled = enable; + + if (!enable) { + wake_up_interruptible(&sunkbd->wait); + cancel_work_sync(&sunkbd->tq); + } +} + +/* + * sunkbd_connect() probes for a Sun keyboard and fills the necessary + * structures. + */ + +static int sunkbd_connect(struct serio *serio, struct serio_driver *drv) +{ + struct sunkbd *sunkbd; + struct input_dev *input_dev; + int err = -ENOMEM; + int i; + + sunkbd = kzalloc_obj(*sunkbd); + input_dev = input_allocate_device(); + if (!sunkbd || !input_dev) + goto fail1; + + sunkbd->serio = serio; + sunkbd->dev = input_dev; + init_waitqueue_head(&sunkbd->wait); + INIT_WORK(&sunkbd->tq, sunkbd_reinit); + snprintf(sunkbd->phys, sizeof(sunkbd->phys), "%s/input0", serio->phys); + + serio_set_drvdata(serio, sunkbd); + + err = serio_open(serio, drv); + if (err) + goto fail2; + + if (sunkbd_initialize(sunkbd) < 0) { + err = -ENODEV; + goto fail3; + } + + snprintf(sunkbd->name, sizeof(sunkbd->name), + "Sun Type %d keyboard", sunkbd->type); + memcpy(sunkbd->keycode, sunkbd_keycode, sizeof(sunkbd->keycode)); + + input_dev->name = sunkbd->name; + input_dev->phys = sunkbd->phys; + input_dev->id.bustype = BUS_RS232; + input_dev->id.vendor = SERIO_SUNKBD; + input_dev->id.product = sunkbd->type; + input_dev->id.version = 0x0100; + input_dev->dev.parent = &serio->dev; + + input_set_drvdata(input_dev, sunkbd); + + input_dev->event = sunkbd_event; + + input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_LED) | + BIT_MASK(EV_SND) | BIT_MASK(EV_REP); + input_dev->ledbit[0] = BIT_MASK(LED_CAPSL) | BIT_MASK(LED_COMPOSE) | + BIT_MASK(LED_SCROLLL) | BIT_MASK(LED_NUML); + input_dev->sndbit[0] = BIT_MASK(SND_CLICK) | BIT_MASK(SND_BELL); + + input_dev->keycode = sunkbd->keycode; + input_dev->keycodesize = sizeof(unsigned char); + input_dev->keycodemax = ARRAY_SIZE(sunkbd_keycode); + for (i = 0; i < ARRAY_SIZE(sunkbd_keycode); i++) + __set_bit(sunkbd->keycode[i], input_dev->keybit); + __clear_bit(KEY_RESERVED, input_dev->keybit); + + sunkbd_enable(sunkbd, true); + + err = input_register_device(sunkbd->dev); + if (err) + goto fail4; + + return 0; + + fail4: sunkbd_enable(sunkbd, false); + fail3: serio_close(serio); + fail2: serio_set_drvdata(serio, NULL); + fail1: input_free_device(input_dev); + kfree(sunkbd); + return err; +} + +/* + * sunkbd_disconnect() unregisters and closes behind us. + */ + +static void sunkbd_disconnect(struct serio *serio) +{ + struct sunkbd *sunkbd = serio_get_drvdata(serio); + + sunkbd_enable(sunkbd, false); + input_unregister_device(sunkbd->dev); + serio_close(serio); + serio_set_drvdata(serio, NULL); + kfree(sunkbd); +} + +static const struct serio_device_id sunkbd_serio_ids[] = { + { + .type = SERIO_RS232, + .proto = SERIO_SUNKBD, + .id = SERIO_ANY, + .extra = SERIO_ANY, + }, + { + .type = SERIO_RS232, + .proto = SERIO_UNKNOWN, /* sunkbd does probe */ + .id = SERIO_ANY, + .extra = SERIO_ANY, + }, + { 0 } +}; + +MODULE_DEVICE_TABLE(serio, sunkbd_serio_ids); + +static struct serio_driver sunkbd_drv = { + .driver = { + .name = "sunkbd", + }, + .description = DRIVER_DESC, + .id_table = sunkbd_serio_ids, + .interrupt = sunkbd_interrupt, + .connect = sunkbd_connect, + .disconnect = sunkbd_disconnect, +}; + +module_serio_driver(sunkbd_drv); -- cgit v1.3.1