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, 150 insertions, 0 deletions

diff --git a/drivers/hid/hid-gfrm.c b/drivers/hid/hid-gfrm.c
new file mode 100644
index 000000000..f7cc754de
--- /dev/null
+++ b/drivers/hid/hid-gfrm.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * HID driver for Google Fiber TV Box remote controls
+ *
+ * Copyright (c) 2014-2015 Google Inc.
+ *
+ * Author: Petri Gynther <pgynther@google.com>
+ */
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/input.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+#define GFRM100  1  /* Google Fiber GFRM100 (Bluetooth classic) */
+#define GFRM200  2  /* Google Fiber GFRM200 (Bluetooth LE) */
+
+#define GFRM100_SEARCH_KEY_REPORT_ID   0xF7
+#define GFRM100_SEARCH_KEY_DOWN        0x0
+#define GFRM100_SEARCH_KEY_AUDIO_DATA  0x1
+#define GFRM100_SEARCH_KEY_UP          0x2
+
+static u8 search_key_dn[3] = {0x40, 0x21, 0x02};
+static u8 search_key_up[3] = {0x40, 0x00, 0x00};
+
+static int gfrm_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	const struct hid_device_id *id = hid_get_drvdata(hdev);
+	unsigned long hdev_type = id->driver_data;
+
+	if (hdev_type == GFRM100) {
+		if (usage->hid == (HID_UP_CONSUMER | 0x4)) {
+			/* Consumer.0004 -> KEY_INFO */
+			hid_map_usage_clear(hi, usage, bit, max, EV_KEY, KEY_INFO);
+			return 1;
+		}
+
+		if (usage->hid == (HID_UP_CONSUMER | 0x41)) {
+			/* Consumer.0041 -> KEY_OK */
+			hid_map_usage_clear(hi, usage, bit, max, EV_KEY, KEY_OK);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static int gfrm_raw_event(struct hid_device *hdev, struct hid_report *report,
+		u8 *data, int size)
+{
+	const struct hid_device_id *id = hid_get_drvdata(hdev);
+	unsigned long hdev_type = id->driver_data;
+	int ret = 0;
+
+	if (hdev_type != GFRM100)
+		return 0;
+
+	if (size < 2 || data[0] != GFRM100_SEARCH_KEY_REPORT_ID)
+		return 0;
+
+	/*
+	 * Convert GFRM100 Search key reports into Consumer.0221 (Key.Search)
+	 * reports. Ignore audio data.
+	 */
+	switch (data[1]) {
+	case GFRM100_SEARCH_KEY_DOWN:
+		ret = hid_report_raw_event(hdev, HID_INPUT_REPORT, search_key_dn,
+					   sizeof(search_key_dn), sizeof(search_key_dn), 1);
+		break;
+
+	case GFRM100_SEARCH_KEY_AUDIO_DATA:
+		break;
+
+	case GFRM100_SEARCH_KEY_UP:
+		ret = hid_report_raw_event(hdev, HID_INPUT_REPORT, search_key_up,
+					   sizeof(search_key_up), sizeof(search_key_up), 1);
+		break;
+
+	default:
+		break;
+	}
+
+	return (ret < 0) ? ret : -1;
+}
+
+static int gfrm_input_configured(struct hid_device *hid, struct hid_input *hidinput)
+{
+	/*
+	 * Enable software autorepeat with:
+	 * - repeat delay: 400 msec
+	 * - repeat period: 100 msec
+	 */
+	input_enable_softrepeat(hidinput->input, 400, 100);
+	return 0;
+}
+
+static int gfrm_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	int ret;
+
+	hid_set_drvdata(hdev, (void *)id);
+
+	ret = hid_parse(hdev);
+	if (ret)
+		goto done;
+
+	if (id->driver_data == GFRM100) {
+		/*
+		 * GFRM100 HID Report Descriptor does not describe the Search
+		 * key reports. Thus, we need to add it manually here, so that
+		 * those reports reach gfrm_raw_event() from hid_input_report().
+		 */
+		if (!hid_register_report(hdev, HID_INPUT_REPORT,
+					 GFRM100_SEARCH_KEY_REPORT_ID, 0)) {
+			ret = -ENOMEM;
+			goto done;
+		}
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+done:
+	return ret;
+}
+
+static const struct hid_device_id gfrm_devices[] = {
+	{ HID_BLUETOOTH_DEVICE(0x58, 0x2000),
+		.driver_data = GFRM100 },
+	{ HID_BLUETOOTH_DEVICE(0x471, 0x2210),
+		.driver_data = GFRM200 },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, gfrm_devices);
+
+static struct hid_driver gfrm_driver = {
+	.name = "gfrm",
+	.id_table = gfrm_devices,
+	.probe = gfrm_probe,
+	.input_mapping = gfrm_input_mapping,
+	.raw_event = gfrm_raw_event,
+	.input_configured = gfrm_input_configured,
+};
+
+module_hid_driver(gfrm_driver);
+
+MODULE_AUTHOR("Petri Gynther <pgynther@google.com>");
+MODULE_DESCRIPTION("Google Fiber TV Box remote control driver");
+MODULE_LICENSE("GPL");