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, 408 insertions, 0 deletions

diff --git a/drivers/input/joystick/grip.c b/drivers/input/joystick/grip.c
new file mode 100644
index 000000000..2a3f768a7
--- /dev/null
+++ b/drivers/input/joystick/grip.c
@@ -0,0 +1,408 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 1998-2001 Vojtech Pavlik
+ */
+
+/*
+ * Gravis/Kensington GrIP protocol joystick and gamepad driver for Linux
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/gameport.h>
+#include <linux/input.h>
+#include <linux/jiffies.h>
+
+#define DRIVER_DESC	"Gravis GrIP protocol joystick driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+#define GRIP_MODE_GPP		1
+#define GRIP_MODE_BD		2
+#define GRIP_MODE_XT		3
+#define GRIP_MODE_DC		4
+
+#define GRIP_LENGTH_GPP		24
+#define GRIP_STROBE_GPP		200	/* 200 us */
+#define GRIP_LENGTH_XT		4
+#define GRIP_STROBE_XT		64	/* 64 us */
+#define GRIP_MAX_CHUNKS_XT	10
+#define GRIP_MAX_BITS_XT	30
+
+struct grip {
+	struct gameport *gameport;
+	struct input_dev *dev[2];
+	unsigned char mode[2];
+	int reads;
+	int bads;
+	char phys[2][32];
+};
+
+static int grip_btn_gpp[] = { BTN_START, BTN_SELECT, BTN_TR2, BTN_Y, 0, BTN_TL2, BTN_A, BTN_B, BTN_X, 0, BTN_TL, BTN_TR, -1 };
+static int grip_btn_bd[] = { BTN_THUMB, BTN_THUMB2, BTN_TRIGGER, BTN_TOP, BTN_BASE, -1 };
+static int grip_btn_xt[] = { BTN_TRIGGER, BTN_THUMB, BTN_A, BTN_B, BTN_C, BTN_X, BTN_Y, BTN_Z, BTN_SELECT, BTN_START, BTN_MODE, -1 };
+static int grip_btn_dc[] = { BTN_TRIGGER, BTN_THUMB, BTN_TOP, BTN_TOP2, BTN_BASE, BTN_BASE2, BTN_BASE3, BTN_BASE4, BTN_BASE5, -1 };
+
+static int grip_abs_gpp[] = { ABS_X, ABS_Y, -1 };
+static int grip_abs_bd[] = { ABS_X, ABS_Y, ABS_THROTTLE, ABS_HAT0X, ABS_HAT0Y, -1 };
+static int grip_abs_xt[] = { ABS_X, ABS_Y, ABS_BRAKE, ABS_GAS, ABS_THROTTLE, ABS_HAT0X, ABS_HAT0Y, ABS_HAT1X, ABS_HAT1Y, -1 };
+static int grip_abs_dc[] = { ABS_X, ABS_Y, ABS_RX, ABS_RY, ABS_THROTTLE, ABS_HAT0X, ABS_HAT0Y, -1 };
+
+static char *grip_name[] = { NULL, "Gravis GamePad Pro", "Gravis Blackhawk Digital",
+				"Gravis Xterminator Digital", "Gravis Xterminator DualControl" };
+static int *grip_abs[] = { NULL, grip_abs_gpp, grip_abs_bd, grip_abs_xt, grip_abs_dc };
+static int *grip_btn[] = { NULL, grip_btn_gpp, grip_btn_bd, grip_btn_xt, grip_btn_dc };
+static char grip_anx[] = { 0, 0, 3, 5, 5 };
+static char grip_cen[] = { 0, 0, 2, 2, 4 };
+
+/*
+ * grip_gpp_read_packet() reads a Gravis GamePad Pro packet.
+ */
+
+static int grip_gpp_read_packet(struct gameport *gameport, int shift, unsigned int *data)
+{
+	unsigned long flags;
+	unsigned char u, v;
+	unsigned int t;
+	int i;
+
+	int strobe = gameport_time(gameport, GRIP_STROBE_GPP);
+
+	data[0] = 0;
+	t = strobe;
+	i = 0;
+
+	local_irq_save(flags);
+
+	v = gameport_read(gameport) >> shift;
+
+	do {
+		t--;
+		u = v; v = (gameport_read(gameport) >> shift) & 3;
+		if (~v & u & 1) {
+			data[0] |= (v >> 1) << i++;
+			t = strobe;
+		}
+	} while (i < GRIP_LENGTH_GPP && t > 0);
+
+	local_irq_restore(flags);
+
+	if (i < GRIP_LENGTH_GPP) return -1;
+
+	for (i = 0; i < GRIP_LENGTH_GPP && (data[0] & 0xfe4210) ^ 0x7c0000; i++)
+		data[0] = data[0] >> 1 | (data[0] & 1) << (GRIP_LENGTH_GPP - 1);
+
+	return -(i == GRIP_LENGTH_GPP);
+}
+
+/*
+ * grip_xt_read_packet() reads a Gravis Xterminator packet.
+ */
+
+static int grip_xt_read_packet(struct gameport *gameport, int shift, unsigned int *data)
+{
+	unsigned int i, j, buf, crc;
+	unsigned char u, v, w;
+	unsigned long flags;
+	unsigned int t;
+	char status;
+
+	int strobe = gameport_time(gameport, GRIP_STROBE_XT);
+
+	data[0] = data[1] = data[2] = data[3] = 0;
+	status = buf = i = j = 0;
+	t = strobe;
+
+	local_irq_save(flags);
+
+	v = w = (gameport_read(gameport) >> shift) & 3;
+
+	do {
+		t--;
+		u = (gameport_read(gameport) >> shift) & 3;
+
+		if (u ^ v) {
+
+			if ((u ^ v) & 1) {
+				buf = (buf << 1) | (u >> 1);
+				t = strobe;
+				i++;
+			} else
+
+			if ((((u ^ v) & (v ^ w)) >> 1) & ~(u | v | w) & 1) {
+				if (i == 20) {
+					crc = buf ^ (buf >> 7) ^ (buf >> 14);
+					if (!((crc ^ (0x25cb9e70 >> ((crc >> 2) & 0x1c))) & 0xf)) {
+						data[buf >> 18] = buf >> 4;
+						status |= 1 << (buf >> 18);
+					}
+					j++;
+				}
+				t = strobe;
+				buf = 0;
+				i = 0;
+			}
+			w = v;
+			v = u;
+		}
+
+	} while (status != 0xf && i < GRIP_MAX_BITS_XT && j < GRIP_MAX_CHUNKS_XT && t > 0);
+
+	local_irq_restore(flags);
+
+	return -(status != 0xf);
+}
+
+/*
+ * grip_timer() repeatedly polls the joysticks and generates events.
+ */
+
+static void grip_poll(struct gameport *gameport)
+{
+	struct grip *grip = gameport_get_drvdata(gameport);
+	unsigned int data[GRIP_LENGTH_XT];
+	struct input_dev *dev;
+	int i, j;
+
+	for (i = 0; i < 2; i++) {
+
+		dev = grip->dev[i];
+		if (!dev)
+			continue;
+
+		grip->reads++;
+
+		switch (grip->mode[i]) {
+
+			case GRIP_MODE_GPP:
+
+				if (grip_gpp_read_packet(grip->gameport, (i << 1) + 4, data)) {
+					grip->bads++;
+					break;
+				}
+
+				input_report_abs(dev, ABS_X, ((*data >> 15) & 1) - ((*data >> 16) & 1));
+				input_report_abs(dev, ABS_Y, ((*data >> 13) & 1) - ((*data >> 12) & 1));
+
+				for (j = 0; j < 12; j++)
+					if (grip_btn_gpp[j])
+						input_report_key(dev, grip_btn_gpp[j], (*data >> j) & 1);
+
+				break;
+
+			case GRIP_MODE_BD:
+
+				if (grip_xt_read_packet(grip->gameport, (i << 1) + 4, data)) {
+					grip->bads++;
+					break;
+				}
+
+				input_report_abs(dev, ABS_X,        (data[0] >> 2) & 0x3f);
+				input_report_abs(dev, ABS_Y,  63 - ((data[0] >> 8) & 0x3f));
+				input_report_abs(dev, ABS_THROTTLE, (data[2] >> 8) & 0x3f);
+
+				input_report_abs(dev, ABS_HAT0X, ((data[2] >> 1) & 1) - ( data[2]       & 1));
+				input_report_abs(dev, ABS_HAT0Y, ((data[2] >> 2) & 1) - ((data[2] >> 3) & 1));
+
+				for (j = 0; j < 5; j++)
+					input_report_key(dev, grip_btn_bd[j], (data[3] >> (j + 4)) & 1);
+
+				break;
+
+			case GRIP_MODE_XT:
+
+				if (grip_xt_read_packet(grip->gameport, (i << 1) + 4, data)) {
+					grip->bads++;
+					break;
+				}
+
+				input_report_abs(dev, ABS_X,        (data[0] >> 2) & 0x3f);
+				input_report_abs(dev, ABS_Y,  63 - ((data[0] >> 8) & 0x3f));
+				input_report_abs(dev, ABS_BRAKE,    (data[1] >> 2) & 0x3f);
+				input_report_abs(dev, ABS_GAS,	    (data[1] >> 8) & 0x3f);
+				input_report_abs(dev, ABS_THROTTLE, (data[2] >> 8) & 0x3f);
+
+				input_report_abs(dev, ABS_HAT0X, ((data[2] >> 1) & 1) - ( data[2]       & 1));
+				input_report_abs(dev, ABS_HAT0Y, ((data[2] >> 2) & 1) - ((data[2] >> 3) & 1));
+				input_report_abs(dev, ABS_HAT1X, ((data[2] >> 5) & 1) - ((data[2] >> 4) & 1));
+				input_report_abs(dev, ABS_HAT1Y, ((data[2] >> 6) & 1) - ((data[2] >> 7) & 1));
+
+				for (j = 0; j < 11; j++)
+					input_report_key(dev, grip_btn_xt[j], (data[3] >> (j + 3)) & 1);
+				break;
+
+			case GRIP_MODE_DC:
+
+				if (grip_xt_read_packet(grip->gameport, (i << 1) + 4, data)) {
+					grip->bads++;
+					break;
+				}
+
+				input_report_abs(dev, ABS_X,        (data[0] >> 2) & 0x3f);
+				input_report_abs(dev, ABS_Y,        (data[0] >> 8) & 0x3f);
+				input_report_abs(dev, ABS_RX,       (data[1] >> 2) & 0x3f);
+				input_report_abs(dev, ABS_RY,	    (data[1] >> 8) & 0x3f);
+				input_report_abs(dev, ABS_THROTTLE, (data[2] >> 8) & 0x3f);
+
+				input_report_abs(dev, ABS_HAT0X, ((data[2] >> 1) & 1) - ( data[2]       & 1));
+				input_report_abs(dev, ABS_HAT0Y, ((data[2] >> 2) & 1) - ((data[2] >> 3) & 1));
+
+				for (j = 0; j < 9; j++)
+					input_report_key(dev, grip_btn_dc[j], (data[3] >> (j + 3)) & 1);
+				break;
+
+
+		}
+
+		input_sync(dev);
+	}
+}
+
+static int grip_open(struct input_dev *dev)
+{
+	struct grip *grip = input_get_drvdata(dev);
+
+	gameport_start_polling(grip->gameport);
+	return 0;
+}
+
+static void grip_close(struct input_dev *dev)
+{
+	struct grip *grip = input_get_drvdata(dev);
+
+	gameport_stop_polling(grip->gameport);
+}
+
+static int grip_connect(struct gameport *gameport, struct gameport_driver *drv)
+{
+	struct grip *grip;
+	struct input_dev *input_dev;
+	unsigned int data[GRIP_LENGTH_XT];
+	int i, j, t;
+	int err;
+
+	grip = kzalloc_obj(*grip);
+	if (!grip)
+		return -ENOMEM;
+
+	grip->gameport = gameport;
+
+	gameport_set_drvdata(gameport, grip);
+
+	err = gameport_open(gameport, drv, GAMEPORT_MODE_RAW);
+	if (err)
+		goto fail1;
+
+	for (i = 0; i < 2; i++) {
+		if (!grip_gpp_read_packet(gameport, (i << 1) + 4, data)) {
+			grip->mode[i] = GRIP_MODE_GPP;
+			continue;
+		}
+		if (!grip_xt_read_packet(gameport, (i << 1) + 4, data)) {
+			if (!(data[3] & 7)) {
+				grip->mode[i] = GRIP_MODE_BD;
+				continue;
+			}
+			if (!(data[2] & 0xf0)) {
+				grip->mode[i] = GRIP_MODE_XT;
+				continue;
+			}
+			grip->mode[i] = GRIP_MODE_DC;
+			continue;
+		}
+	}
+
+	if (!grip->mode[0] && !grip->mode[1]) {
+		err = -ENODEV;
+		goto fail2;
+	}
+
+	gameport_set_poll_handler(gameport, grip_poll);
+	gameport_set_poll_interval(gameport, 20);
+
+	for (i = 0; i < 2; i++) {
+		if (!grip->mode[i])
+			continue;
+
+		grip->dev[i] = input_dev = input_allocate_device();
+		if (!input_dev) {
+			err = -ENOMEM;
+			goto fail3;
+		}
+
+		snprintf(grip->phys[i], sizeof(grip->phys[i]),
+			 "%s/input%d", gameport->phys, i);
+
+		input_dev->name = grip_name[grip->mode[i]];
+		input_dev->phys = grip->phys[i];
+		input_dev->id.bustype = BUS_GAMEPORT;
+		input_dev->id.vendor = GAMEPORT_ID_VENDOR_GRAVIS;
+		input_dev->id.product = grip->mode[i];
+		input_dev->id.version = 0x0100;
+		input_dev->dev.parent = &gameport->dev;
+
+		input_set_drvdata(input_dev, grip);
+
+		input_dev->open = grip_open;
+		input_dev->close = grip_close;
+
+		input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+
+		for (j = 0; (t = grip_abs[grip->mode[i]][j]) >= 0; j++) {
+
+			if (j < grip_cen[grip->mode[i]])
+				input_set_abs_params(input_dev, t, 14, 52, 1, 2);
+			else if (j < grip_anx[grip->mode[i]])
+				input_set_abs_params(input_dev, t, 3, 57, 1, 0);
+			else
+				input_set_abs_params(input_dev, t, -1, 1, 0, 0);
+		}
+
+		for (j = 0; (t = grip_btn[grip->mode[i]][j]) >= 0; j++)
+			if (t > 0)
+				set_bit(t, input_dev->keybit);
+
+		err = input_register_device(grip->dev[i]);
+		if (err)
+			goto fail4;
+	}
+
+	return 0;
+
+ fail4:	input_free_device(grip->dev[i]);
+ fail3:	while (--i >= 0)
+		if (grip->dev[i])
+			input_unregister_device(grip->dev[i]);
+ fail2:	gameport_close(gameport);
+ fail1:	gameport_set_drvdata(gameport, NULL);
+	kfree(grip);
+	return err;
+}
+
+static void grip_disconnect(struct gameport *gameport)
+{
+	struct grip *grip = gameport_get_drvdata(gameport);
+	int i;
+
+	for (i = 0; i < 2; i++)
+		if (grip->dev[i])
+			input_unregister_device(grip->dev[i]);
+	gameport_close(gameport);
+	gameport_set_drvdata(gameport, NULL);
+	kfree(grip);
+}
+
+static struct gameport_driver grip_drv = {
+	.driver		= {
+		.name	= "grip",
+		.owner	= THIS_MODULE,
+	},
+	.description	= DRIVER_DESC,
+	.connect	= grip_connect,
+	.disconnect	= grip_disconnect,
+};
+
+module_gameport_driver(grip_drv);