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, 396 insertions, 0 deletions

diff --git a/drivers/input/joystick/a3d.c b/drivers/input/joystick/a3d.c
new file mode 100644
index 000000000..48a145796
--- /dev/null
+++ b/drivers/input/joystick/a3d.c
@@ -0,0 +1,396 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 1998-2001 Vojtech Pavlik
+ */
+
+/*
+ * FP-Gaming Assassin 3D joystick 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	"FP-Gaming Assassin 3D joystick driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+#define A3D_MAX_START		600	/* 600 us */
+#define A3D_MAX_STROBE		80	/* 80 us */
+#define A3D_MAX_LENGTH		40	/* 40*3 bits */
+
+#define A3D_MODE_A3D		1	/* Assassin 3D */
+#define A3D_MODE_PAN		2	/* Panther */
+#define A3D_MODE_OEM		3	/* Panther OEM version */
+#define A3D_MODE_PXL		4	/* Panther XL */
+
+static char *a3d_names[] = { NULL, "FP-Gaming Assassin 3D", "MadCatz Panther", "OEM Panther",
+			"MadCatz Panther XL", "MadCatz Panther XL w/ rudder" };
+
+struct a3d {
+	struct gameport *gameport;
+	struct gameport *adc;
+	struct input_dev *dev;
+	int axes[4];
+	int buttons;
+	int mode;
+	int length;
+	int reads;
+	int bads;
+	char phys[32];
+};
+
+/*
+ * a3d_read_packet() reads an Assassin 3D packet.
+ */
+
+static int a3d_read_packet(struct gameport *gameport, int length, char *data)
+{
+	unsigned long flags;
+	unsigned char u, v;
+	unsigned int t, s;
+	int i;
+
+	i = 0;
+	t = gameport_time(gameport, A3D_MAX_START);
+	s = gameport_time(gameport, A3D_MAX_STROBE);
+
+	local_irq_save(flags);
+	gameport_trigger(gameport);
+	v = gameport_read(gameport);
+
+	while (t > 0 && i < length) {
+		t--;
+		u = v; v = gameport_read(gameport);
+		if (~v & u & 0x10) {
+			data[i++] = v >> 5;
+			t = s;
+		}
+	}
+
+	local_irq_restore(flags);
+
+	return i;
+}
+
+/*
+ * a3d_csum() computes checksum of triplet packet
+ */
+
+static int a3d_csum(char *data, int count)
+{
+	int i, csum = 0;
+
+	for (i = 0; i < count - 2; i++)
+		csum += data[i];
+	return (csum & 0x3f) != ((data[count - 2] << 3) | data[count - 1]);
+}
+
+static void a3d_read(struct a3d *a3d, unsigned char *data)
+{
+	struct input_dev *dev = a3d->dev;
+
+	switch (a3d->mode) {
+
+		case A3D_MODE_A3D:
+		case A3D_MODE_OEM:
+		case A3D_MODE_PAN:
+
+			input_report_rel(dev, REL_X, ((data[5] << 6) | (data[6] << 3) | data[ 7]) - ((data[5] & 4) << 7));
+			input_report_rel(dev, REL_Y, ((data[8] << 6) | (data[9] << 3) | data[10]) - ((data[8] & 4) << 7));
+
+			input_report_key(dev, BTN_RIGHT,  data[2] & 1);
+			input_report_key(dev, BTN_LEFT,   data[3] & 2);
+			input_report_key(dev, BTN_MIDDLE, data[3] & 4);
+
+			input_sync(dev);
+
+			a3d->axes[0] = ((signed char)((data[11] << 6) | (data[12] << 3) | (data[13]))) + 128;
+			a3d->axes[1] = ((signed char)((data[14] << 6) | (data[15] << 3) | (data[16]))) + 128;
+			a3d->axes[2] = ((signed char)((data[17] << 6) | (data[18] << 3) | (data[19]))) + 128;
+			a3d->axes[3] = ((signed char)((data[20] << 6) | (data[21] << 3) | (data[22]))) + 128;
+
+			a3d->buttons = ((data[3] << 3) | data[4]) & 0xf;
+
+			break;
+
+		case A3D_MODE_PXL:
+
+			input_report_rel(dev, REL_X, ((data[ 9] << 6) | (data[10] << 3) | data[11]) - ((data[ 9] & 4) << 7));
+			input_report_rel(dev, REL_Y, ((data[12] << 6) | (data[13] << 3) | data[14]) - ((data[12] & 4) << 7));
+
+			input_report_key(dev, BTN_RIGHT,  data[2] & 1);
+			input_report_key(dev, BTN_LEFT,   data[3] & 2);
+			input_report_key(dev, BTN_MIDDLE, data[3] & 4);
+			input_report_key(dev, BTN_SIDE,   data[7] & 2);
+			input_report_key(dev, BTN_EXTRA,  data[7] & 4);
+
+			input_report_abs(dev, ABS_X,        ((signed char)((data[15] << 6) | (data[16] << 3) | (data[17]))) + 128);
+			input_report_abs(dev, ABS_Y,        ((signed char)((data[18] << 6) | (data[19] << 3) | (data[20]))) + 128);
+			input_report_abs(dev, ABS_RUDDER,   ((signed char)((data[21] << 6) | (data[22] << 3) | (data[23]))) + 128);
+			input_report_abs(dev, ABS_THROTTLE, ((signed char)((data[24] << 6) | (data[25] << 3) | (data[26]))) + 128);
+
+			input_report_abs(dev, ABS_HAT0X, ( data[5]       & 1) - ((data[5] >> 2) & 1));
+			input_report_abs(dev, ABS_HAT0Y, ((data[5] >> 1) & 1) - ((data[6] >> 2) & 1));
+			input_report_abs(dev, ABS_HAT1X, ((data[4] >> 1) & 1) - ( data[3]       & 1));
+			input_report_abs(dev, ABS_HAT1Y, ((data[4] >> 2) & 1) - ( data[4]       & 1));
+
+			input_report_key(dev, BTN_TRIGGER, data[8] & 1);
+			input_report_key(dev, BTN_THUMB,   data[8] & 2);
+			input_report_key(dev, BTN_TOP,     data[8] & 4);
+			input_report_key(dev, BTN_PINKIE,  data[7] & 1);
+
+			input_sync(dev);
+
+			break;
+	}
+}
+
+
+/*
+ * a3d_poll() reads and analyzes A3D joystick data.
+ */
+
+static void a3d_poll(struct gameport *gameport)
+{
+	struct a3d *a3d = gameport_get_drvdata(gameport);
+	unsigned char data[A3D_MAX_LENGTH];
+
+	a3d->reads++;
+	if (a3d_read_packet(a3d->gameport, a3d->length, data) != a3d->length ||
+	    data[0] != a3d->mode || a3d_csum(data, a3d->length))
+		a3d->bads++;
+	else
+		a3d_read(a3d, data);
+}
+
+/*
+ * a3d_adc_cooked_read() copies the acis and button data to the
+ * callers arrays. It could do the read itself, but the caller could
+ * call this more than 50 times a second, which would use too much CPU.
+ */
+
+static int a3d_adc_cooked_read(struct gameport *gameport, int *axes, int *buttons)
+{
+	struct a3d *a3d = gameport->port_data;
+	int i;
+
+	for (i = 0; i < 4; i++)
+		axes[i] = (a3d->axes[i] < 254) ? a3d->axes[i] : -1;
+	*buttons = a3d->buttons;
+	return 0;
+}
+
+/*
+ * a3d_adc_open() is the gameport open routine. It refuses to serve
+ * any but cooked data.
+ */
+
+static int a3d_adc_open(struct gameport *gameport, int mode)
+{
+	struct a3d *a3d = gameport->port_data;
+
+	if (mode != GAMEPORT_MODE_COOKED)
+		return -1;
+
+	gameport_start_polling(a3d->gameport);
+	return 0;
+}
+
+/*
+ * a3d_adc_close() is a callback from the input close routine.
+ */
+
+static void a3d_adc_close(struct gameport *gameport)
+{
+	struct a3d *a3d = gameport->port_data;
+
+	gameport_stop_polling(a3d->gameport);
+}
+
+/*
+ * a3d_open() is a callback from the input open routine.
+ */
+
+static int a3d_open(struct input_dev *dev)
+{
+	struct a3d *a3d = input_get_drvdata(dev);
+
+	gameport_start_polling(a3d->gameport);
+	return 0;
+}
+
+/*
+ * a3d_close() is a callback from the input close routine.
+ */
+
+static void a3d_close(struct input_dev *dev)
+{
+	struct a3d *a3d = input_get_drvdata(dev);
+
+	gameport_stop_polling(a3d->gameport);
+}
+
+/*
+ * a3d_connect() probes for A3D joysticks.
+ */
+
+static int a3d_connect(struct gameport *gameport, struct gameport_driver *drv)
+{
+	struct a3d *a3d;
+	struct input_dev *input_dev;
+	struct gameport *adc;
+	unsigned char data[A3D_MAX_LENGTH];
+	int i;
+	int err;
+
+	a3d = kzalloc_obj(*a3d);
+	input_dev = input_allocate_device();
+	if (!a3d || !input_dev) {
+		err = -ENOMEM;
+		goto fail1;
+	}
+
+	a3d->dev = input_dev;
+	a3d->gameport = gameport;
+
+	gameport_set_drvdata(gameport, a3d);
+
+	err = gameport_open(gameport, drv, GAMEPORT_MODE_RAW);
+	if (err)
+		goto fail1;
+
+	i = a3d_read_packet(gameport, A3D_MAX_LENGTH, data);
+
+	if (!i || a3d_csum(data, i)) {
+		err = -ENODEV;
+		goto fail2;
+	}
+
+	a3d->mode = data[0];
+
+	if (!a3d->mode || a3d->mode > 5) {
+		printk(KERN_WARNING "a3d.c: Unknown A3D device detected "
+			"(%s, id=%d), contact <vojtech@ucw.cz>\n", gameport->phys, a3d->mode);
+		err = -ENODEV;
+		goto fail2;
+	}
+
+	gameport_set_poll_handler(gameport, a3d_poll);
+	gameport_set_poll_interval(gameport, 20);
+
+	snprintf(a3d->phys, sizeof(a3d->phys), "%s/input0", gameport->phys);
+
+	input_dev->name = a3d_names[a3d->mode];
+	input_dev->phys = a3d->phys;
+	input_dev->id.bustype = BUS_GAMEPORT;
+	input_dev->id.vendor = GAMEPORT_ID_VENDOR_MADCATZ;
+	input_dev->id.product = a3d->mode;
+	input_dev->id.version = 0x0100;
+	input_dev->dev.parent = &gameport->dev;
+	input_dev->open = a3d_open;
+	input_dev->close = a3d_close;
+
+	input_set_drvdata(input_dev, a3d);
+
+	if (a3d->mode == A3D_MODE_PXL) {
+
+		int axes[] = { ABS_X, ABS_Y, ABS_THROTTLE, ABS_RUDDER };
+
+		a3d->length = 33;
+
+		input_dev->evbit[0] |= BIT_MASK(EV_ABS) | BIT_MASK(EV_KEY) |
+			BIT_MASK(EV_REL);
+		input_dev->relbit[0] |= BIT_MASK(REL_X) | BIT_MASK(REL_Y);
+		input_dev->absbit[0] |= BIT_MASK(ABS_X) | BIT_MASK(ABS_Y) |
+			BIT_MASK(ABS_THROTTLE) | BIT_MASK(ABS_RUDDER) |
+			BIT_MASK(ABS_HAT0X) | BIT_MASK(ABS_HAT0Y) |
+			BIT_MASK(ABS_HAT1X) | BIT_MASK(ABS_HAT1Y);
+		input_dev->keybit[BIT_WORD(BTN_MOUSE)] |= BIT_MASK(BTN_RIGHT) |
+			BIT_MASK(BTN_LEFT) | BIT_MASK(BTN_MIDDLE) |
+			BIT_MASK(BTN_SIDE) | BIT_MASK(BTN_EXTRA);
+		input_dev->keybit[BIT_WORD(BTN_JOYSTICK)] |=
+			BIT_MASK(BTN_TRIGGER) | BIT_MASK(BTN_THUMB) |
+			BIT_MASK(BTN_TOP) | BIT_MASK(BTN_PINKIE);
+
+		a3d_read(a3d, data);
+
+		for (i = 0; i < 4; i++) {
+			if (i < 2)
+				input_set_abs_params(input_dev, axes[i],
+					48, input_abs_get_val(input_dev, axes[i]) * 2 - 48, 0, 8);
+			else
+				input_set_abs_params(input_dev, axes[i], 2, 253, 0, 0);
+			input_set_abs_params(input_dev, ABS_HAT0X + i, -1, 1, 0, 0);
+		}
+
+	} else {
+		a3d->length = 29;
+
+		input_dev->evbit[0] |= BIT_MASK(EV_KEY) | BIT_MASK(EV_REL);
+		input_dev->relbit[0] |= BIT_MASK(REL_X) | BIT_MASK(REL_Y);
+		input_dev->keybit[BIT_WORD(BTN_MOUSE)] |= BIT_MASK(BTN_RIGHT) |
+			BIT_MASK(BTN_LEFT) | BIT_MASK(BTN_MIDDLE);
+
+		a3d_read(a3d, data);
+
+		if (!(a3d->adc = adc = gameport_allocate_port()))
+			printk(KERN_ERR "a3d: Not enough memory for ADC port\n");
+		else {
+			adc->port_data = a3d;
+			adc->open = a3d_adc_open;
+			adc->close = a3d_adc_close;
+			adc->cooked_read = a3d_adc_cooked_read;
+			adc->fuzz = 1;
+
+			gameport_set_name(adc, a3d_names[a3d->mode]);
+			gameport_set_phys(adc, "%s/gameport0", gameport->phys);
+			adc->dev.parent = &gameport->dev;
+
+			gameport_register_port(adc);
+		}
+	}
+
+	err = input_register_device(a3d->dev);
+	if (err)
+		goto fail3;
+
+	return 0;
+
+ fail3:	if (a3d->adc)
+		gameport_unregister_port(a3d->adc);
+ fail2:	gameport_close(gameport);
+ fail1:	gameport_set_drvdata(gameport, NULL);
+	input_free_device(input_dev);
+	kfree(a3d);
+	return err;
+}
+
+static void a3d_disconnect(struct gameport *gameport)
+{
+	struct a3d *a3d = gameport_get_drvdata(gameport);
+
+	input_unregister_device(a3d->dev);
+	if (a3d->adc)
+		gameport_unregister_port(a3d->adc);
+	gameport_close(gameport);
+	gameport_set_drvdata(gameport, NULL);
+	kfree(a3d);
+}
+
+static struct gameport_driver a3d_drv = {
+	.driver		= {
+		.name	= "adc",
+		.owner	= THIS_MODULE,
+	},
+	.description	= DRIVER_DESC,
+	.connect	= a3d_connect,
+	.disconnect	= a3d_disconnect,
+};
+
+module_gameport_driver(a3d_drv);