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, 246 insertions, 0 deletions

diff --git a/drivers/hid/hid-cmedia.c b/drivers/hid/hid-cmedia.c
new file mode 100644
index 000000000..7b3dd4197
--- /dev/null
+++ b/drivers/hid/hid-cmedia.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * HID driver for CMedia CM6533 audio jack controls
+ * and HS100B mute buttons
+ *
+ * Copyright (C) 2015 Ben Chen <ben_chen@bizlinktech.com>
+ * Copyright (C) 2021 Thomas Weißschuh <linux@weissschuh.net>
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include "hid-ids.h"
+
+MODULE_AUTHOR("Ben Chen");
+MODULE_AUTHOR("Thomas Weißschuh");
+MODULE_DESCRIPTION("CM6533 HID jack controls and HS100B mute button");
+MODULE_LICENSE("GPL");
+
+#define CM6533_JD_TYPE_COUNT      1
+#define CM6533_JD_RAWEV_LEN	 16
+#define CM6533_JD_SFX_OFFSET	  8
+
+#define HS100B_RDESC_ORIG_SIZE   60
+
+/* Fixed report descriptor of HS-100B audio chip
+ * Bit 4 is an abolute Microphone mute usage instead of being unassigned.
+ */
+static const __u8 hs100b_rdesc_fixed[] = {
+	0x05, 0x0C,         /*  Usage Page (Consumer),          */
+	0x09, 0x01,         /*  Usage (Consumer Control),       */
+	0xA1, 0x01,         /*  Collection (Application),       */
+	0x15, 0x00,         /*      Logical Minimum (0),        */
+	0x25, 0x01,         /*      Logical Maximum (1),        */
+	0x09, 0xE9,         /*      Usage (Volume Inc),         */
+	0x09, 0xEA,         /*      Usage (Volume Dec),         */
+	0x75, 0x01,         /*      Report Size (1),            */
+	0x95, 0x02,         /*      Report Count (2),           */
+	0x81, 0x02,         /*      Input (Variable),           */
+	0x09, 0xE2,         /*      Usage (Mute),               */
+	0x95, 0x01,         /*      Report Count (1),           */
+	0x81, 0x06,         /*      Input (Variable, Relative), */
+	0x05, 0x0B,         /*      Usage Page (Telephony),     */
+	0x09, 0x2F,         /*      Usage (2Fh),                */
+	0x81, 0x02,         /*      Input (Variable),           */
+	0x09, 0x20,         /*      Usage (20h),                */
+	0x81, 0x06,         /*      Input (Variable, Relative), */
+	0x05, 0x0C,         /*      Usage Page (Consumer),      */
+	0x09, 0x00,         /*      Usage (00h),                */
+	0x95, 0x03,         /*      Report Count (3),           */
+	0x81, 0x02,         /*      Input (Variable),           */
+	0x26, 0xFF, 0x00,   /*      Logical Maximum (255),      */
+	0x09, 0x00,         /*      Usage (00h),                */
+	0x75, 0x08,         /*      Report Size (8),            */
+	0x95, 0x03,         /*      Report Count (3),           */
+	0x81, 0x02,         /*      Input (Variable),           */
+	0x09, 0x00,         /*      Usage (00h),                */
+	0x95, 0x04,         /*      Report Count (4),           */
+	0x91, 0x02,         /*      Output (Variable),          */
+	0xC0                /*  End Collection                  */
+};
+
+/*
+*
+*CM6533 audio jack HID raw events:
+*
+*Plug in:
+*01000600 002083xx 080008c0 10000000
+*about 3 seconds later...
+*01000a00 002083xx 08000380 10000000
+*01000600 002083xx 08000380 10000000
+*
+*Plug out:
+*01000400 002083xx 080008c0 x0000000
+*/
+
+static const u8 ji_sfx[] = { 0x08, 0x00, 0x08, 0xc0 };
+static const u8 ji_in[]  = { 0x01, 0x00, 0x06, 0x00 };
+static const u8 ji_out[] = { 0x01, 0x00, 0x04, 0x00 };
+
+static int jack_switch_types[CM6533_JD_TYPE_COUNT] = {
+	SW_HEADPHONE_INSERT,
+};
+
+struct cmhid {
+	struct input_dev *input_dev;
+	struct hid_device *hid;
+	unsigned short switch_map[CM6533_JD_TYPE_COUNT];
+};
+
+static void hp_ev(struct hid_device *hid, struct cmhid *cm, int value)
+{
+	input_report_switch(cm->input_dev, SW_HEADPHONE_INSERT, value);
+	input_sync(cm->input_dev);
+}
+
+static int cmhid_raw_event(struct hid_device *hid, struct hid_report *report,
+	 u8 *data, int len)
+{
+	struct cmhid *cm = hid_get_drvdata(hid);
+
+	if (len != CM6533_JD_RAWEV_LEN || !(hid->claimed & HID_CLAIMED_INPUT))
+		goto out;
+	if (memcmp(data+CM6533_JD_SFX_OFFSET, ji_sfx, sizeof(ji_sfx)))
+		goto out;
+
+	if (!memcmp(data, ji_out, sizeof(ji_out))) {
+		hp_ev(hid, cm, 0);
+		goto out;
+	}
+	if (!memcmp(data, ji_in, sizeof(ji_in))) {
+		hp_ev(hid, cm, 1);
+		goto out;
+	}
+
+out:
+	return 0;
+}
+
+static int cmhid_input_configured(struct hid_device *hid,
+		struct hid_input *hidinput)
+{
+	struct input_dev *input_dev = hidinput->input;
+	struct cmhid *cm = hid_get_drvdata(hid);
+	int i;
+
+	cm->input_dev = input_dev;
+	memcpy(cm->switch_map, jack_switch_types, sizeof(cm->switch_map));
+	input_dev->evbit[0] = BIT(EV_SW);
+	for (i = 0; i < CM6533_JD_TYPE_COUNT; i++)
+		input_set_capability(cm->input_dev,
+				EV_SW, jack_switch_types[i]);
+	return 0;
+}
+
+static int cmhid_input_mapping(struct hid_device *hid,
+		struct hid_input *hi, struct hid_field *field,
+		struct hid_usage *usage, unsigned long **bit, int *max)
+{
+	return -1;
+}
+
+static int cmhid_probe(struct hid_device *hid, const struct hid_device_id *id)
+{
+	int ret;
+	struct cmhid *cm;
+
+	cm = kzalloc_obj(struct cmhid);
+	if (!cm) {
+		ret = -ENOMEM;
+		goto allocfail;
+	}
+
+	cm->hid = hid;
+
+	hid->quirks |= HID_QUIRK_HIDINPUT_FORCE;
+	hid_set_drvdata(hid, cm);
+
+	ret = hid_parse(hid);
+	if (ret) {
+		hid_err(hid, "parse failed\n");
+		goto fail;
+	}
+
+	ret = hid_hw_start(hid, HID_CONNECT_DEFAULT | HID_CONNECT_HIDDEV_FORCE);
+	if (ret) {
+		hid_err(hid, "hw start failed\n");
+		goto fail;
+	}
+
+	return 0;
+fail:
+	kfree(cm);
+allocfail:
+	return ret;
+}
+
+static void cmhid_remove(struct hid_device *hid)
+{
+	struct cmhid *cm = hid_get_drvdata(hid);
+
+	hid_hw_stop(hid);
+	kfree(cm);
+}
+
+static const struct hid_device_id cmhid_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CMEDIA, USB_DEVICE_ID_CM6533) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, cmhid_devices);
+
+static struct hid_driver cmhid_driver = {
+	.name = "cm6533_jd",
+	.id_table = cmhid_devices,
+	.raw_event = cmhid_raw_event,
+	.input_configured = cmhid_input_configured,
+	.probe = cmhid_probe,
+	.remove = cmhid_remove,
+	.input_mapping = cmhid_input_mapping,
+};
+
+static const __u8 *cmhid_hs100b_report_fixup(struct hid_device *hid, __u8 *rdesc,
+				       unsigned int *rsize)
+{
+	if (*rsize == HS100B_RDESC_ORIG_SIZE) {
+		hid_info(hid, "Fixing CMedia HS-100B report descriptor\n");
+		*rsize = sizeof(hs100b_rdesc_fixed);
+		return hs100b_rdesc_fixed;
+	}
+	return rdesc;
+}
+
+static const struct hid_device_id cmhid_hs100b_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CMEDIA, USB_DEVICE_ID_CMEDIA_HS100B) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, cmhid_hs100b_devices);
+
+static struct hid_driver cmhid_hs100b_driver = {
+	.name = "cmedia_hs100b",
+	.id_table = cmhid_hs100b_devices,
+	.report_fixup = cmhid_hs100b_report_fixup,
+};
+
+static int cmedia_init(void)
+{
+	int ret;
+
+	ret = hid_register_driver(&cmhid_driver);
+	if (ret)
+		return ret;
+
+	ret = hid_register_driver(&cmhid_hs100b_driver);
+	if (ret)
+		hid_unregister_driver(&cmhid_driver);
+
+	return ret;
+}
+module_init(cmedia_init);
+
+static void cmedia_exit(void)
+{
+		hid_unregister_driver(&cmhid_driver);
+		hid_unregister_driver(&cmhid_hs100b_driver);
+}
+module_exit(cmedia_exit);