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/misc/apanel.c | 304 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 304 insertions(+) create mode 100644 drivers/input/misc/apanel.c (limited to 'drivers/input/misc/apanel.c') diff --git a/drivers/input/misc/apanel.c b/drivers/input/misc/apanel.c new file mode 100644 index 000000000..3eb02a64a --- /dev/null +++ b/drivers/input/misc/apanel.c @@ -0,0 +1,304 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Fujitsu Lifebook Application Panel button drive + * + * Copyright (C) 2007 Stephen Hemminger + * Copyright (C) 2001-2003 Jochen Eisinger + * + * Many Fujitsu Lifebook laptops have a small panel of buttons that are + * accessible via the i2c/smbus interface. This driver polls those + * buttons and generates input events. + * + * For more details see: + * http://apanel.sourceforge.net/tech.php + */ + +#include +#include +#include +#include +#include +#include +#include + +#define APANEL_NAME "Fujitsu Application Panel" +#define APANEL "apanel" + +/* How often we poll keys - msecs */ +#define POLL_INTERVAL_DEFAULT 1000 + +/* Magic constants in BIOS that tell about buttons */ +enum apanel_devid { + APANEL_DEV_NONE = 0, + APANEL_DEV_APPBTN = 1, + APANEL_DEV_CDBTN = 2, + APANEL_DEV_LCD = 3, + APANEL_DEV_LED = 4, + + APANEL_DEV_MAX, +}; + +enum apanel_chip { + CHIP_NONE = 0, + CHIP_OZ992C = 1, + CHIP_OZ163T = 2, + CHIP_OZ711M3 = 4, +}; + +/* Result of BIOS snooping/probing -- what features are supported */ +static enum apanel_chip device_chip[APANEL_DEV_MAX]; + +#define MAX_PANEL_KEYS 12 + +struct apanel { + struct input_dev *idev; + struct i2c_client *client; + unsigned short keymap[MAX_PANEL_KEYS]; + u16 nkeys; + struct led_classdev mail_led; +}; + +static const unsigned short apanel_keymap[MAX_PANEL_KEYS] = { + [0] = KEY_MAIL, + [1] = KEY_WWW, + [2] = KEY_PROG2, + [3] = KEY_PROG1, + + [8] = KEY_FORWARD, + [9] = KEY_REWIND, + [10] = KEY_STOPCD, + [11] = KEY_PLAYPAUSE, +}; + +static void report_key(struct input_dev *input, unsigned keycode) +{ + dev_dbg(input->dev.parent, "report key %#x\n", keycode); + input_report_key(input, keycode, 1); + input_sync(input); + + input_report_key(input, keycode, 0); + input_sync(input); +} + +/* Poll for key changes + * + * Read Application keys via SMI + * A (0x4), B (0x8), Internet (0x2), Email (0x1). + * + * CD keys: + * Forward (0x100), Rewind (0x200), Stop (0x400), Pause (0x800) + */ +static void apanel_poll(struct input_dev *idev) +{ + struct apanel *ap = input_get_drvdata(idev); + u8 cmd = device_chip[APANEL_DEV_APPBTN] == CHIP_OZ992C ? 0 : 8; + s32 data; + int i; + + data = i2c_smbus_read_word_data(ap->client, cmd); + if (data < 0) + return; /* ignore errors (due to ACPI??) */ + + /* write back to clear latch */ + i2c_smbus_write_word_data(ap->client, cmd, 0); + + if (!data) + return; + + dev_dbg(&idev->dev, APANEL ": data %#x\n", data); + for (i = 0; i < idev->keycodemax; i++) + if ((1u << i) & data) + report_key(idev, ap->keymap[i]); +} + +static int mail_led_set(struct led_classdev *led, + enum led_brightness value) +{ + struct apanel *ap = container_of(led, struct apanel, mail_led); + u16 led_bits = value != LED_OFF ? 0x8000 : 0x0000; + + return i2c_smbus_write_word_data(ap->client, 0x10, led_bits); +} + +static int apanel_probe(struct i2c_client *client) +{ + struct apanel *ap; + struct input_dev *idev; + u8 cmd = device_chip[APANEL_DEV_APPBTN] == CHIP_OZ992C ? 0 : 8; + int i, err; + + ap = devm_kzalloc(&client->dev, sizeof(*ap), GFP_KERNEL); + if (!ap) + return -ENOMEM; + + idev = devm_input_allocate_device(&client->dev); + if (!idev) + return -ENOMEM; + + ap->idev = idev; + ap->client = client; + + i2c_set_clientdata(client, ap); + + err = i2c_smbus_write_word_data(client, cmd, 0); + if (err) { + dev_warn(&client->dev, "smbus write error %d\n", err); + return err; + } + + input_set_drvdata(idev, ap); + + idev->name = APANEL_NAME " buttons"; + idev->phys = "apanel/input0"; + idev->id.bustype = BUS_HOST; + + memcpy(ap->keymap, apanel_keymap, sizeof(apanel_keymap)); + idev->keycode = ap->keymap; + idev->keycodesize = sizeof(ap->keymap[0]); + idev->keycodemax = (device_chip[APANEL_DEV_CDBTN] != CHIP_NONE) ? 12 : 4; + + set_bit(EV_KEY, idev->evbit); + for (i = 0; i < idev->keycodemax; i++) + if (ap->keymap[i]) + set_bit(ap->keymap[i], idev->keybit); + + err = input_setup_polling(idev, apanel_poll); + if (err) + return err; + + input_set_poll_interval(idev, POLL_INTERVAL_DEFAULT); + + err = input_register_device(idev); + if (err) + return err; + + if (device_chip[APANEL_DEV_LED] != CHIP_NONE) { + ap->mail_led.name = "mail:blue"; + ap->mail_led.brightness_set_blocking = mail_led_set; + err = devm_led_classdev_register(&client->dev, &ap->mail_led); + if (err) + return err; + } + + return 0; +} + +static void apanel_shutdown(struct i2c_client *client) +{ + struct apanel *ap = i2c_get_clientdata(client); + + if (device_chip[APANEL_DEV_LED] != CHIP_NONE) + led_set_brightness(&ap->mail_led, LED_OFF); +} + +static const struct i2c_device_id apanel_id[] = { + { .name = "fujitsu_apanel" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, apanel_id); + +static struct i2c_driver apanel_driver = { + .driver = { + .name = APANEL, + }, + .probe = apanel_probe, + .shutdown = apanel_shutdown, + .id_table = apanel_id, +}; + +/* Scan the system ROM for the signature "FJKEYINF" */ +static __init const void __iomem *bios_signature(const void __iomem *bios) +{ + ssize_t offset; + const unsigned char signature[] = "FJKEYINF"; + + for (offset = 0; offset < 0x10000; offset += 0x10) { + if (check_signature(bios + offset, signature, + sizeof(signature)-1)) + return bios + offset; + } + pr_notice(APANEL ": Fujitsu BIOS signature '%s' not found...\n", + signature); + return NULL; +} + +static int __init apanel_init(void) +{ + void __iomem *bios; + const void __iomem *p; + u8 devno; + unsigned char i2c_addr; + int found = 0; + + bios = ioremap(0xF0000, 0x10000); /* Can't fail */ + + p = bios_signature(bios); + if (!p) { + iounmap(bios); + return -ENODEV; + } + + /* just use the first address */ + p += 8; + i2c_addr = readb(p + 3) >> 1; + + for ( ; (devno = readb(p)) & 0x7f; p += 4) { + unsigned char method, slave, chip; + + method = readb(p + 1); + chip = readb(p + 2); + slave = readb(p + 3) >> 1; + + if (slave != i2c_addr) { + pr_notice(APANEL ": only one SMBus slave " + "address supported, skipping device...\n"); + continue; + } + + /* translate alternative device numbers */ + switch (devno) { + case 6: + devno = APANEL_DEV_APPBTN; + break; + case 7: + devno = APANEL_DEV_LED; + break; + } + + if (devno >= APANEL_DEV_MAX) + pr_notice(APANEL ": unknown device %u found\n", devno); + else if (device_chip[devno] != CHIP_NONE) + pr_warn(APANEL ": duplicate entry for devno %u\n", + devno); + + else if (method != 1 && method != 2 && method != 4) { + pr_notice(APANEL ": unknown method %u for devno %u\n", + method, devno); + } else { + device_chip[devno] = (enum apanel_chip) chip; + ++found; + } + } + iounmap(bios); + + if (found == 0) { + pr_info(APANEL ": no input devices reported by BIOS\n"); + return -EIO; + } + + return i2c_add_driver(&apanel_driver); +} +module_init(apanel_init); + +static void __exit apanel_cleanup(void) +{ + i2c_del_driver(&apanel_driver); +} +module_exit(apanel_cleanup); + +MODULE_AUTHOR("Stephen Hemminger "); +MODULE_DESCRIPTION(APANEL_NAME " driver"); +MODULE_LICENSE("GPL"); + +MODULE_ALIAS("dmi:*:svnFUJITSU:pnLifeBook*:pvr*:rvnFUJITSU:*"); +MODULE_ALIAS("dmi:*:svnFUJITSU:pnLifebook*:pvr*:rvnFUJITSU:*"); -- cgit v1.3.1