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/mouse/atarimouse.c | 153 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 153 insertions(+) create mode 100644 drivers/input/mouse/atarimouse.c (limited to 'drivers/input/mouse/atarimouse.c') diff --git a/drivers/input/mouse/atarimouse.c b/drivers/input/mouse/atarimouse.c new file mode 100644 index 000000000..b1219cc4d --- /dev/null +++ b/drivers/input/mouse/atarimouse.c @@ -0,0 +1,153 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Atari mouse driver for Linux/m68k + * + * Copyright (c) 2005 Michael Schmitz + * + * Based on: + * Amiga mouse driver for Linux/m68k + * + * Copyright (c) 2000-2002 Vojtech Pavlik + */ +/* + * The low level init and interrupt stuff is handled in arch/mm68k/atari/atakeyb.c + * (the keyboard ACIA also handles the mouse and joystick data, and the keyboard + * interrupt is shared with the MIDI ACIA so MIDI data also get handled there). + * This driver only deals with handing key events off to the input layer. + * + * Largely based on the old: + * + * Atari Mouse Driver for Linux + * by Robert de Vries (robert@and.nl) 19Jul93 + * + * 16 Nov 1994 Andreas Schwab + * Compatibility with busmouse + * Support for three button mouse (shamelessly stolen from MiNT) + * third button wired to one of the joystick directions on joystick 1 + * + * 1996/02/11 Andreas Schwab + * Module support + * Allow multiple open's + * + * Converted to use new generic busmouse code. 5 Apr 1998 + * Russell King + */ + + + +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include + +MODULE_AUTHOR("Michael Schmitz "); +MODULE_DESCRIPTION("Atari mouse driver"); +MODULE_LICENSE("GPL"); + +static int mouse_threshold[2] = {2, 2}; +module_param_array(mouse_threshold, int, NULL, 0); + +#ifdef FIXED_ATARI_JOYSTICK +extern int atari_mouse_buttons; +#endif + +static struct input_dev *atamouse_dev; + +static void atamouse_interrupt(char *buf) +{ + int buttons, dx, dy; + + buttons = (buf[0] & 1) | ((buf[0] & 2) << 1); +#ifdef FIXED_ATARI_JOYSTICK + buttons |= atari_mouse_buttons & 2; + atari_mouse_buttons = buttons; +#endif + + /* only relative events get here */ + dx = buf[1]; + dy = buf[2]; + + input_report_rel(atamouse_dev, REL_X, dx); + input_report_rel(atamouse_dev, REL_Y, dy); + + input_report_key(atamouse_dev, BTN_LEFT, buttons & 0x4); + input_report_key(atamouse_dev, BTN_MIDDLE, buttons & 0x2); + input_report_key(atamouse_dev, BTN_RIGHT, buttons & 0x1); + + input_sync(atamouse_dev); + + return; +} + +static int atamouse_open(struct input_dev *dev) +{ +#ifdef FIXED_ATARI_JOYSTICK + atari_mouse_buttons = 0; +#endif + ikbd_mouse_y0_top(); + ikbd_mouse_thresh(mouse_threshold[0], mouse_threshold[1]); + ikbd_mouse_rel_pos(); + atari_input_mouse_interrupt_hook = atamouse_interrupt; + + return 0; +} + +static void atamouse_close(struct input_dev *dev) +{ + ikbd_mouse_disable(); + atari_input_mouse_interrupt_hook = NULL; +} + +static int __init atamouse_init(void) +{ + int error; + + if (!MACH_IS_ATARI || !ATARIHW_PRESENT(ST_MFP)) + return -ENODEV; + + error = atari_keyb_init(); + if (error) + return error; + + atamouse_dev = input_allocate_device(); + if (!atamouse_dev) + return -ENOMEM; + + atamouse_dev->name = "Atari mouse"; + atamouse_dev->phys = "atamouse/input0"; + atamouse_dev->id.bustype = BUS_HOST; + atamouse_dev->id.vendor = 0x0001; + atamouse_dev->id.product = 0x0002; + atamouse_dev->id.version = 0x0100; + + atamouse_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REL); + atamouse_dev->relbit[0] = BIT_MASK(REL_X) | BIT_MASK(REL_Y); + atamouse_dev->keybit[BIT_WORD(BTN_LEFT)] = BIT_MASK(BTN_LEFT) | + BIT_MASK(BTN_MIDDLE) | BIT_MASK(BTN_RIGHT); + + atamouse_dev->open = atamouse_open; + atamouse_dev->close = atamouse_close; + + error = input_register_device(atamouse_dev); + if (error) { + input_free_device(atamouse_dev); + return error; + } + + return 0; +} + +static void __exit atamouse_exit(void) +{ + input_unregister_device(atamouse_dev); +} + +module_init(atamouse_init); +module_exit(atamouse_exit); -- cgit v1.3.1