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, 156 insertions, 0 deletions

diff --git a/drivers/hid/hid-lgff.c b/drivers/hid/hid-lgff.c
new file mode 100644
index 000000000..aed4ddc39
--- /dev/null
+++ b/drivers/hid/hid-lgff.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Force feedback support for hid-compliant for some of the devices from
+ * Logitech, namely:
+ * - WingMan Cordless RumblePad
+ * - WingMan Force 3D
+ *
+ *  Copyright (c) 2002-2004 Johann Deneux
+ *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
+ */
+
+/*
+ *
+ * Should you need to contact me, the author, you can do so by
+ * e-mail - mail your message to <johann.deneux@it.uu.se>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/input.h>
+#include <linux/hid.h>
+
+#include "hid-lg.h"
+
+struct dev_type {
+	u16 idVendor;
+	u16 idProduct;
+	const signed short *ff;
+};
+
+static const signed short ff_rumble[] = {
+	FF_RUMBLE,
+	-1
+};
+
+static const signed short ff_joystick[] = {
+	FF_CONSTANT,
+	-1
+};
+
+static const signed short ff_joystick_ac[] = {
+	FF_CONSTANT,
+	FF_AUTOCENTER,
+	-1
+};
+
+static const struct dev_type devices[] = {
+	{ 0x046d, 0xc211, ff_rumble },
+	{ 0x046d, 0xc219, ff_rumble },
+	{ 0x046d, 0xc283, ff_joystick },
+	{ 0x046d, 0xc286, ff_joystick_ac },
+	{ 0x046d, 0xc287, ff_joystick_ac },
+	{ 0x046d, 0xc293, ff_joystick },
+	{ 0x046d, 0xc295, ff_joystick },
+};
+
+static int hid_lgff_play(struct input_dev *dev, void *data, struct ff_effect *effect)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
+	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
+	int x, y;
+	unsigned int left, right;
+
+#define CLAMP(x) if (x < 0) x = 0; if (x > 0xff) x = 0xff
+
+	switch (effect->type) {
+	case FF_CONSTANT:
+		x = effect->u.ramp.start_level + 0x7f;	/* 0x7f is center */
+		y = effect->u.ramp.end_level + 0x7f;
+		CLAMP(x);
+		CLAMP(y);
+		report->field[0]->value[0] = 0x51;
+		report->field[0]->value[1] = 0x08;
+		report->field[0]->value[2] = x;
+		report->field[0]->value[3] = y;
+		dbg_hid("(x, y)=(%04x, %04x)\n", x, y);
+		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+		break;
+
+	case FF_RUMBLE:
+		right = effect->u.rumble.strong_magnitude;
+		left = effect->u.rumble.weak_magnitude;
+		right = right * 0xff / 0xffff;
+		left = left * 0xff / 0xffff;
+		CLAMP(left);
+		CLAMP(right);
+		report->field[0]->value[0] = 0x42;
+		report->field[0]->value[1] = 0x00;
+		report->field[0]->value[2] = left;
+		report->field[0]->value[3] = right;
+		dbg_hid("(left, right)=(%04x, %04x)\n", left, right);
+		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+		break;
+	}
+	return 0;
+}
+
+static void hid_lgff_set_autocenter(struct input_dev *dev, u16 magnitude)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
+	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
+	__s32 *value = report->field[0]->value;
+	magnitude = (magnitude >> 12) & 0xf;
+	*value++ = 0xfe;
+	*value++ = 0x0d;
+	*value++ = magnitude;   /* clockwise strength */
+	*value++ = magnitude;   /* counter-clockwise strength */
+	*value++ = 0x80;
+	*value++ = 0x00;
+	*value = 0x00;
+	hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+}
+
+int lgff_init(struct hid_device* hid)
+{
+	struct hid_input *hidinput;
+	struct input_dev *dev;
+	const signed short *ff_bits = ff_joystick;
+	int error;
+	int i;
+
+	if (list_empty(&hid->inputs)) {
+		hid_err(hid, "no inputs found\n");
+		return -ENODEV;
+	}
+	hidinput = list_entry(hid->inputs.next, struct hid_input, list);
+	dev = hidinput->input;
+
+	/* Check that the report looks ok */
+	if (!hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 7))
+		return -ENODEV;
+
+	for (i = 0; i < ARRAY_SIZE(devices); i++) {
+		if (dev->id.vendor == devices[i].idVendor &&
+		    dev->id.product == devices[i].idProduct) {
+			ff_bits = devices[i].ff;
+			break;
+		}
+	}
+
+	for (i = 0; ff_bits[i] >= 0; i++)
+		set_bit(ff_bits[i], dev->ffbit);
+
+	error = input_ff_create_memless(dev, NULL, hid_lgff_play);
+	if (error)
+		return error;
+
+	if ( test_bit(FF_AUTOCENTER, dev->ffbit) )
+		dev->ff->set_autocenter = hid_lgff_set_autocenter;
+
+	pr_info("Force feedback for Logitech force feedback devices by Johann Deneux <johann.deneux@it.uu.se>\n");
+
+	return 0;
+}