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, 173 insertions, 0 deletions

diff --git a/drivers/hid/hid-elecom.c b/drivers/hid/hid-elecom.c
new file mode 100644
index 000000000..37d88ce57
--- /dev/null
+++ b/drivers/hid/hid-elecom.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for ELECOM devices:
+ *  - BM084 Bluetooth Mouse
+ *  - EX-G Trackballs (M-XT3DRBK, M-XT3URBK, M-XT4DRBK)
+ *  - DEFT Trackballs (M-DT1DRBK, M-DT1URBK, M-DT2DRBK, M-DT2URBK)
+ *  - HUGE Trackballs (M-HT1DRBK, M-HT1URBK)
+ *  - HUGE Plus Trackball (M-HT1MRBK)
+ *
+ *  Copyright (c) 2010 Richard Nauber <Richard.Nauber@gmail.com>
+ *  Copyright (c) 2016 Yuxuan Shui <yshuiv7@gmail.com>
+ *  Copyright (c) 2017 Diego Elio Pettenò <flameeyes@flameeyes.eu>
+ *  Copyright (c) 2017 Alex Manoussakis <amanou@gnu.org>
+ *  Copyright (c) 2017 Tomasz Kramkowski <tk@the-tk.com>
+ *  Copyright (c) 2020 YOSHIOKA Takuma <lo48576@hard-wi.red>
+ *  Copyright (c) 2022 Takahiro Fujii <fujii@xaxxi.net>
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+/*
+ * Certain ELECOM mice misreport their button count meaning that they only work
+ * correctly with the ELECOM mouse assistant software which is unavailable for
+ * Linux. A four extra INPUT reports and a FEATURE report are described by the
+ * report descriptor but it does not appear that these enable software to
+ * control what the extra buttons map to. The only simple and straightforward
+ * solution seems to involve fixing up the report descriptor.
+ */
+#define MOUSE_BUTTONS_MAX 8
+static void mouse_button_fixup(struct hid_device *hdev,
+			       __u8 *rdesc, unsigned int rsize,
+			       unsigned int button_bit_count,
+			       unsigned int padding_bit,
+			       unsigned int button_report_size,
+			       unsigned int button_usage_maximum,
+			       int nbuttons)
+{
+	if (rsize < 32 || rdesc[button_bit_count] != 0x95 ||
+	    rdesc[button_report_size] != 0x75 ||
+	    rdesc[button_report_size + 1] != 0x01 ||
+	    rdesc[button_usage_maximum] != 0x29 || rdesc[padding_bit] != 0x75)
+		return;
+	hid_info(hdev, "Fixing up Elecom mouse button count\n");
+	nbuttons = clamp(nbuttons, 0, MOUSE_BUTTONS_MAX);
+	rdesc[button_bit_count + 1] = nbuttons;
+	rdesc[button_usage_maximum + 1] = nbuttons;
+	rdesc[padding_bit + 1] = MOUSE_BUTTONS_MAX - nbuttons;
+}
+
+static const __u8 *elecom_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	switch (hdev->product) {
+	case USB_DEVICE_ID_ELECOM_BM084:
+		/* The BM084 Bluetooth mouse includes a non-existing horizontal
+		 * wheel in the HID descriptor. */
+		if (*rsize >= 48 && rdesc[46] == 0x05 && rdesc[47] == 0x0c) {
+			hid_info(hdev, "Fixing up Elecom BM084 report descriptor\n");
+			rdesc[47] = 0x00;
+		}
+		break;
+	case USB_DEVICE_ID_ELECOM_M_XGL20DLBK:
+		/*
+		 * Report descriptor format:
+		 * 20: button bit count
+		 * 28: padding bit count
+		 * 22: button report size
+		 * 14: button usage maximum
+		 */
+		mouse_button_fixup(hdev, rdesc, *rsize, 20, 28, 22, 14, 8);
+		break;
+	case USB_DEVICE_ID_ELECOM_M_XT3URBK_00FB:
+	case USB_DEVICE_ID_ELECOM_M_XT3URBK_018F:
+	case USB_DEVICE_ID_ELECOM_M_XT3DRBK_00FC:
+	case USB_DEVICE_ID_ELECOM_M_XT4DRBK:
+		/*
+		 * Report descriptor format:
+		 * 12: button bit count
+		 * 30: padding bit count
+		 * 14: button report size
+		 * 20: button usage maximum
+		 */
+		mouse_button_fixup(hdev, rdesc, *rsize, 12, 30, 14, 20, 6);
+		break;
+	case USB_DEVICE_ID_ELECOM_M_DT1URBK:
+	case USB_DEVICE_ID_ELECOM_M_DT1DRBK:
+	case USB_DEVICE_ID_ELECOM_M_HT1URBK_010C:
+	case USB_DEVICE_ID_ELECOM_M_HT1URBK_019B:
+	case USB_DEVICE_ID_ELECOM_M_HT1DRBK_010D:
+		/*
+		 * Report descriptor format:
+		 * 12: button bit count
+		 * 30: padding bit count
+		 * 14: button report size
+		 * 20: button usage maximum
+		 */
+		mouse_button_fixup(hdev, rdesc, *rsize, 12, 30, 14, 20, 8);
+		break;
+	case USB_DEVICE_ID_ELECOM_M_XT3DRBK_018C:
+		/*
+		 * Report descriptor format:
+		 * 22: button bit count
+		 * 30: padding bit count
+		 * 24: button report size
+		 * 16: button usage maximum
+		 */
+		mouse_button_fixup(hdev, rdesc, *rsize, 22, 30, 24, 16, 6);
+		break;
+	case USB_DEVICE_ID_ELECOM_M_DT2DRBK:
+	case USB_DEVICE_ID_ELECOM_M_HT1DRBK_011C:
+		/*
+		 * Report descriptor format:
+		 * 22: button bit count
+		 * 30: padding bit count
+		 * 24: button report size
+		 * 16: button usage maximum
+		 */
+		mouse_button_fixup(hdev, rdesc, *rsize, 22, 30, 24, 16, 8);
+		break;
+	case USB_DEVICE_ID_ELECOM_M_HT1MRBK:
+	case USB_DEVICE_ID_ELECOM_M_HT1MRBK_01AB:
+	case USB_DEVICE_ID_ELECOM_M_HT1MRBK_01AC:
+		/*
+		 * Report descriptor format:
+		 * 24: button bit count
+		 * 28: padding bit count
+		 * 22: button report size
+		 * 16: button usage maximum
+		 */
+		mouse_button_fixup(hdev, rdesc, *rsize, 24, 28, 22, 16, 8);
+		break;
+	}
+	return rdesc;
+}
+
+static const struct hid_device_id elecom_devices[] = {
+	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_BM084) },
+	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1MRBK_01AC) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XGL20DLBK) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3URBK_00FB) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3URBK_018F) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3DRBK_00FC) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3DRBK_018C) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT4DRBK) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1URBK) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1DRBK) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT2DRBK) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1URBK_010C) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1URBK_019B) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1DRBK_010D) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1DRBK_011C) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1MRBK) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1MRBK_01AB) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, elecom_devices);
+
+static struct hid_driver elecom_driver = {
+	.name = "elecom",
+	.id_table = elecom_devices,
+	.report_fixup = elecom_report_fixup
+};
+module_hid_driver(elecom_driver);
+
+MODULE_DESCRIPTION("HID driver for ELECOM devices");
+MODULE_LICENSE("GPL");