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/ps3/vuart.h | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 89 insertions(+) create mode 100644 drivers/ps3/vuart.h (limited to 'drivers/ps3/vuart.h') diff --git a/drivers/ps3/vuart.h b/drivers/ps3/vuart.h new file mode 100644 index 000000000..64d34efef --- /dev/null +++ b/drivers/ps3/vuart.h @@ -0,0 +1,89 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * PS3 virtual uart + * + * Copyright (C) 2006 Sony Computer Entertainment Inc. + * Copyright 2006 Sony Corp. + */ + +#if !defined(_PS3_VUART_H) +#define _PS3_VUART_H + +#include + +struct ps3_vuart_stats { + unsigned long bytes_written; + unsigned long bytes_read; + unsigned long tx_interrupts; + unsigned long rx_interrupts; + unsigned long disconnect_interrupts; +}; + +struct ps3_vuart_work { + struct work_struct work; + unsigned long trigger; + struct ps3_system_bus_device *dev; /* to convert work to device */ +}; + +/** + * struct ps3_vuart_port_driver - a driver for a device on a vuart port + */ + +struct ps3_vuart_port_driver { + struct ps3_system_bus_driver core; + int (*probe)(struct ps3_system_bus_device *); + int (*remove)(struct ps3_system_bus_device *); + void (*shutdown)(struct ps3_system_bus_device *); + void (*work)(struct ps3_system_bus_device *); + /* int (*tx_event)(struct ps3_system_bus_device *dev); */ + /* int (*rx_event)(struct ps3_system_bus_device *dev); */ + /* int (*disconnect_event)(struct ps3_system_bus_device *dev); */ + /* int (*suspend)(struct ps3_system_bus_device *, pm_message_t); */ + /* int (*resume)(struct ps3_system_bus_device *); */ +}; + +int ps3_vuart_port_driver_register(struct ps3_vuart_port_driver *drv); +void ps3_vuart_port_driver_unregister(struct ps3_vuart_port_driver *drv); + +static inline struct ps3_vuart_port_driver * + ps3_system_bus_dev_to_vuart_drv(struct ps3_system_bus_device *_dev) +{ + struct ps3_system_bus_driver *sbd = + ps3_system_bus_dev_to_system_bus_drv(_dev); + BUG_ON(!sbd); + return container_of(sbd, struct ps3_vuart_port_driver, core); +} +static inline struct ps3_system_bus_device *ps3_vuart_work_to_system_bus_dev( + struct work_struct *_work) +{ + struct ps3_vuart_work *vw = container_of(_work, struct ps3_vuart_work, + work); + return vw->dev; +} + +int ps3_vuart_write(struct ps3_system_bus_device *dev, const void *buf, + unsigned int bytes); +int ps3_vuart_read(struct ps3_system_bus_device *dev, void *buf, + unsigned int bytes); +int ps3_vuart_read_async(struct ps3_system_bus_device *dev, unsigned int bytes); +void ps3_vuart_cancel_async(struct ps3_system_bus_device *dev); +void ps3_vuart_clear_rx_bytes(struct ps3_system_bus_device *dev, + unsigned int bytes); + +struct vuart_triggers { + unsigned long rx; + unsigned long tx; +}; + +int ps3_vuart_get_triggers(struct ps3_system_bus_device *dev, + struct vuart_triggers *trig); +int ps3_vuart_set_triggers(struct ps3_system_bus_device *dev, unsigned int tx, + unsigned int rx); +int ps3_vuart_enable_interrupt_tx(struct ps3_system_bus_device *dev); +int ps3_vuart_disable_interrupt_tx(struct ps3_system_bus_device *dev); +int ps3_vuart_enable_interrupt_rx(struct ps3_system_bus_device *dev); +int ps3_vuart_disable_interrupt_rx(struct ps3_system_bus_device *dev); +int ps3_vuart_enable_interrupt_disconnect(struct ps3_system_bus_device *dev); +int ps3_vuart_disable_interrupt_disconnect(struct ps3_system_bus_device *dev); + +#endif -- cgit v1.3.1