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, 140 insertions, 0 deletions

diff --git a/drivers/hid/hid-gaff.c b/drivers/hid/hid-gaff.c
new file mode 100644
index 000000000..ec793a179
--- /dev/null
+++ b/drivers/hid/hid-gaff.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Force feedback support for GreenAsia (Product ID 0x12) based devices
+ *
+ *  The devices are distributed under various names and the same USB device ID
+ *  can be used in many game controllers.
+ *
+ *  0e8f:0012 "GreenAsia Inc.    USB Joystick     "
+ *   - tested with MANTA Warior MM816 and SpeedLink Strike2 SL-6635.
+ *
+ *  Copyright (c) 2008 Lukasz Lubojanski <lukasz@lubojanski.info>
+ */
+
+/*
+ */
+
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include "hid-ids.h"
+
+#ifdef CONFIG_GREENASIA_FF
+
+struct gaff_device {
+	struct hid_report *report;
+};
+
+static int hid_gaff_play(struct input_dev *dev, void *data,
+			 struct ff_effect *effect)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct gaff_device *gaff = data;
+	int left, right;
+
+	left = effect->u.rumble.strong_magnitude;
+	right = effect->u.rumble.weak_magnitude;
+
+	dbg_hid("called with 0x%04x 0x%04x", left, right);
+
+	left = left * 0xfe / 0xffff;
+	right = right * 0xfe / 0xffff;
+
+	gaff->report->field[0]->value[0] = 0x51;
+	gaff->report->field[0]->value[1] = 0x0;
+	gaff->report->field[0]->value[2] = right;
+	gaff->report->field[0]->value[3] = 0;
+	gaff->report->field[0]->value[4] = left;
+	gaff->report->field[0]->value[5] = 0;
+	dbg_hid("running with 0x%02x 0x%02x", left, right);
+	hid_hw_request(hid, gaff->report, HID_REQ_SET_REPORT);
+
+	gaff->report->field[0]->value[0] = 0xfa;
+	gaff->report->field[0]->value[1] = 0xfe;
+	gaff->report->field[0]->value[2] = 0x0;
+	gaff->report->field[0]->value[4] = 0x0;
+
+	hid_hw_request(hid, gaff->report, HID_REQ_SET_REPORT);
+
+	return 0;
+}
+
+static int gaff_input_configured(struct hid_device *hid, struct hid_input *hidinput)
+{
+	struct gaff_device *gaff;
+	struct hid_report *report;
+	struct list_head *report_list =
+			&hid->report_enum[HID_OUTPUT_REPORT].report_list;
+	struct input_dev *dev = hidinput->input;
+	int error;
+
+	if (!list_is_first(&hidinput->list, &hid->inputs))
+		return 0;
+
+	report = list_first_entry_or_null(report_list, struct hid_report, list);
+	if (!report) {
+		hid_err(hid, "no output reports found\n");
+		return -ENODEV;
+	}
+	if (report->maxfield < 1) {
+		hid_err(hid, "no fields in the report\n");
+		return -ENODEV;
+	}
+
+	if (report->field[0]->report_count < 6) {
+		hid_err(hid, "not enough values in the field\n");
+		return -ENODEV;
+	}
+
+	gaff = kzalloc_obj(struct gaff_device);
+	if (!gaff)
+		return -ENOMEM;
+
+	gaff->report = report;
+	set_bit(FF_RUMBLE, dev->ffbit);
+
+	error = input_ff_create_memless(dev, gaff, hid_gaff_play);
+	if (error) {
+		kfree(gaff);
+		return error;
+	}
+
+	gaff->report->field[0]->value[0] = 0x51;
+	gaff->report->field[0]->value[1] = 0x00;
+	gaff->report->field[0]->value[2] = 0x00;
+	gaff->report->field[0]->value[3] = 0x00;
+	hid_hw_request(hid, gaff->report, HID_REQ_SET_REPORT);
+
+	gaff->report->field[0]->value[0] = 0xfa;
+	gaff->report->field[0]->value[1] = 0xfe;
+
+	hid_hw_request(hid, gaff->report, HID_REQ_SET_REPORT);
+
+	hid_info(hid, "Force Feedback for GreenAsia 0x12 devices by Lukasz Lubojanski <lukasz@lubojanski.info>\n");
+
+	return 0;
+}
+#else
+static inline int gaff_input_configured(struct hid_device *hdev,
+					struct hid_input *hidinput)
+{
+	return 0;
+}
+#endif
+
+static const struct hid_device_id ga_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_GREENASIA, 0x0012),  },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, ga_devices);
+
+static struct hid_driver ga_driver = {
+	.name = "greenasia",
+	.id_table = ga_devices,
+	.input_configured = gaff_input_configured,
+};
+module_hid_driver(ga_driver);
+
+MODULE_DESCRIPTION("Force feedback support for GreenAsia (Product ID 0x12) based devices");
+MODULE_LICENSE("GPL");