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/video/fbdev/macmodes.h | 71 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) create mode 100644 drivers/video/fbdev/macmodes.h (limited to 'drivers/video/fbdev/macmodes.h') diff --git a/drivers/video/fbdev/macmodes.h b/drivers/video/fbdev/macmodes.h new file mode 100644 index 000000000..b86ba08aa --- /dev/null +++ b/drivers/video/fbdev/macmodes.h @@ -0,0 +1,71 @@ +/* + * linux/drivers/video/macmodes.h -- Standard MacOS video modes + * + * Copyright (C) 1998 Geert Uytterhoeven + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file COPYING in the main directory of this archive for + * more details. + */ + +#ifndef _VIDEO_MACMODES_H +#define _VIDEO_MACMODES_H + + /* + * Video mode values. + * These are supposed to be the same as the values that Apple uses in + * MacOS. + */ + +#define VMODE_NVRAM 0 +#define VMODE_512_384_60I 1 /* 512x384, 60Hz interlaced (NTSC) */ +#define VMODE_512_384_60 2 /* 512x384, 60Hz */ +#define VMODE_640_480_50I 3 /* 640x480, 50Hz interlaced (PAL) */ +#define VMODE_640_480_60I 4 /* 640x480, 60Hz interlaced (NTSC) */ +#define VMODE_640_480_60 5 /* 640x480, 60Hz (VGA) */ +#define VMODE_640_480_67 6 /* 640x480, 67Hz */ +#define VMODE_640_870_75P 7 /* 640x870, 75Hz (portrait) */ +#define VMODE_768_576_50I 8 /* 768x576, 50Hz (PAL full frame) */ +#define VMODE_800_600_56 9 /* 800x600, 56Hz */ +#define VMODE_800_600_60 10 /* 800x600, 60Hz */ +#define VMODE_800_600_72 11 /* 800x600, 72Hz */ +#define VMODE_800_600_75 12 /* 800x600, 75Hz */ +#define VMODE_832_624_75 13 /* 832x624, 75Hz */ +#define VMODE_1024_768_60 14 /* 1024x768, 60Hz */ +#define VMODE_1024_768_70 15 /* 1024x768, 70Hz (or 72Hz?) */ +#define VMODE_1024_768_75V 16 /* 1024x768, 75Hz (VESA) */ +#define VMODE_1024_768_75 17 /* 1024x768, 75Hz */ +#define VMODE_1152_870_75 18 /* 1152x870, 75Hz */ +#define VMODE_1280_960_75 19 /* 1280x960, 75Hz */ +#define VMODE_1280_1024_75 20 /* 1280x1024, 75Hz */ +#define VMODE_1152_768_60 21 /* 1152x768, 60Hz Titanium PowerBook */ +#define VMODE_1600_1024_60 22 /* 1600x1024, 60Hz 22" Cinema Display */ +#define VMODE_MAX 22 +#define VMODE_CHOOSE 99 + +#define CMODE_NVRAM -1 +#define CMODE_CHOOSE -2 +#define CMODE_8 0 /* 8 bits/pixel */ +#define CMODE_16 1 /* 16 (actually 15) bits/pixel */ +#define CMODE_32 2 /* 32 (actually 24) bits/pixel */ + + +extern int mac_vmode_to_var(int vmode, int cmode, + struct fb_var_screeninfo *var); +extern int mac_var_to_vmode(const struct fb_var_screeninfo *var, int *vmode, + int *cmode); +extern int mac_map_monitor_sense(int sense); +extern int mac_find_mode(struct fb_var_screeninfo *var, + struct fb_info *info, + const char *mode_option, + unsigned int default_bpp); + + + /* + * Addresses in NVRAM where video mode and pixel size are stored. + */ + +#define NV_VMODE 0x140f +#define NV_CMODE 0x1410 + +#endif /* _VIDEO_MACMODES_H */ -- cgit v1.3.1