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/tdfxfb.c | 1827 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 1827 insertions(+) create mode 100644 drivers/video/fbdev/tdfxfb.c (limited to 'drivers/video/fbdev/tdfxfb.c') diff --git a/drivers/video/fbdev/tdfxfb.c b/drivers/video/fbdev/tdfxfb.c new file mode 100644 index 000000000..281987502 --- /dev/null +++ b/drivers/video/fbdev/tdfxfb.c @@ -0,0 +1,1827 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * + * tdfxfb.c + * + * Author: Hannu Mallat + * + * Copyright © 1999 Hannu Mallat + * All rights reserved + * + * Created : Thu Sep 23 18:17:43 1999, hmallat + * Last modified: Tue Nov 2 21:19:47 1999, hmallat + * + * I2C part copied from the i2c-voodoo3.c driver by: + * Frodo Looijaard , + * Philip Edelbrock , + * Ralph Metzler , and + * Mark D. Studebaker + * + * Lots of the information here comes from the Daryll Strauss' Banshee + * patches to the XF86 server, and the rest comes from the 3dfx + * Banshee specification. I'm very much indebted to Daryll for his + * work on the X server. + * + * Voodoo3 support was contributed Harold Oga. Lots of additions + * (proper acceleration, 24 bpp, hardware cursor) and bug fixes by Attila + * Kesmarki. Thanks guys! + * + * Voodoo1 and Voodoo2 support aren't relevant to this driver as they + * behave very differently from the Voodoo3/4/5. For anyone wanting to + * use frame buffer on the Voodoo1/2, see the sstfb driver (which is + * located at http://www.sourceforge.net/projects/sstfb). + * + * While I _am_ grateful to 3Dfx for releasing the specs for Banshee, + * I do wish the next version is a bit more complete. Without the XF86 + * patches I couldn't have gotten even this far... for instance, the + * extensions to the VGA register set go completely unmentioned in the + * spec! Also, lots of references are made to the 'SST core', but no + * spec is publicly available, AFAIK. + * + * The structure of this driver comes pretty much from the Permedia + * driver by Ilario Nardinocchi, which in turn is based on skeletonfb. + * + * TODO: + * - multihead support (basically need to support an array of fb_infos) + * - support other architectures (PPC, Alpha); does the fact that the VGA + * core can be accessed only thru I/O (not memory mapped) complicate + * things? + * + * Version history: + * + * 0.1.4 (released 2002-05-28) ported over to new fbdev api by James Simmons + * + * 0.1.3 (released 1999-11-02) added Attila's panning support, code + * reorg, hwcursor address page size alignment + * (for mmapping both frame buffer and regs), + * and my changes to get rid of hardcoded + * VGA i/o register locations (uses PCI + * configuration info now) + * 0.1.2 (released 1999-10-19) added Attila Kesmarki's bug fixes and + * improvements + * 0.1.1 (released 1999-10-07) added Voodoo3 support by Harold Oga. + * 0.1.0 (released 1999-10-06) initial version + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include