x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

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) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 41 insertions, 0 deletions

diff --git a/drivers/gpib/include/gpibP.h b/drivers/gpib/include/gpibP.h
new file mode 100644
index 000000000..e3938ada3
--- /dev/null
+++ b/drivers/gpib/include/gpibP.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/***************************************************************************
+ *    copyright		   : (C) 2002,2003 by Frank Mori Hess
+ ***************************************************************************/
+
+#ifndef _GPIB_P_H
+#define _GPIB_P_H
+
+#include <linux/types.h>
+
+#include "gpib_types.h"
+#include "gpib_proto.h"
+#include "gpib_cmd.h"
+#include <linux/gpib.h>
+#include <linux/gpib_ioctl.h>
+
+#include <linux/fs.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+
+int gpib_register_driver(struct gpib_interface *interface, struct module *mod);
+void gpib_unregister_driver(struct gpib_interface *interface);
+struct pci_dev *gpib_pci_get_device(const struct gpib_board_config *config, unsigned int vendor_id,
+				    unsigned int device_id, struct pci_dev *from);
+struct pci_dev *gpib_pci_get_subsys(const struct gpib_board_config *config, unsigned int vendor_id,
+				    unsigned int device_id, unsigned int ss_vendor,
+				    unsigned int ss_device, struct pci_dev *from);
+unsigned int num_gpib_events(const struct gpib_event_queue *queue);
+int push_gpib_event(struct gpib_board *board, short event_type);
+int pop_gpib_event(struct gpib_board *board, struct gpib_event_queue *queue, short *event_type);
+int gpib_request_pseudo_irq(struct gpib_board *board, irqreturn_t (*handler)(int, void *));
+void gpib_free_pseudo_irq(struct gpib_board *board);
+int gpib_match_device_path(struct device *dev, const char *device_path_in);
+
+extern struct gpib_board board_array[GPIB_MAX_NUM_BOARDS];
+
+extern struct list_head registered_drivers;
+
+#endif	// _GPIB_P_H
+