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, 304 insertions, 0 deletions

diff --git a/drivers/input/keyboard/omap-keypad.c b/drivers/input/keyboard/omap-keypad.c
new file mode 100644
index 000000000..589f51d43
--- /dev/null
+++ b/drivers/input/keyboard/omap-keypad.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * linux/drivers/input/keyboard/omap-keypad.c
+ *
+ * OMAP Keypad Driver
+ *
+ * Copyright (C) 2003 Nokia Corporation
+ * Written by Timo Teräs <ext-timo.teras@nokia.com>
+ *
+ * Added support for H2 & H3 Keypad
+ * Copyright (C) 2004 Texas Instruments
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/types.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/mutex.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/platform_data/gpio-omap.h>
+#include <linux/platform_data/keypad-omap.h>
+#include <linux/soc/ti/omap1-io.h>
+
+#undef NEW_BOARD_LEARNING_MODE
+
+static void omap_kp_tasklet(unsigned long);
+static void omap_kp_timer(struct timer_list *);
+
+static unsigned char keypad_state[8];
+static DEFINE_MUTEX(kp_enable_mutex);
+static int kp_enable = 1;
+static int kp_cur_group = -1;
+
+struct omap_kp {
+	struct input_dev *input;
+	struct timer_list timer;
+	int irq;
+	unsigned int rows;
+	unsigned int cols;
+	unsigned long delay;
+	unsigned int debounce;
+	unsigned short keymap[];
+};
+
+static DECLARE_TASKLET_DISABLED_OLD(kp_tasklet, omap_kp_tasklet);
+
+static irqreturn_t omap_kp_interrupt(int irq, void *dev_id)
+{
+	/* disable keyboard interrupt and schedule for handling */
+	omap_writew(1, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+
+	tasklet_schedule(&kp_tasklet);
+
+	return IRQ_HANDLED;
+}
+
+static void omap_kp_timer(struct timer_list *unused)
+{
+	tasklet_schedule(&kp_tasklet);
+}
+
+static void omap_kp_scan_keypad(struct omap_kp *omap_kp, unsigned char *state)
+{
+	int col = 0;
+
+	/* disable keyboard interrupt and schedule for handling */
+	omap_writew(1, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+
+	/* read the keypad status */
+	omap_writew(0xff, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBC);
+	for (col = 0; col < omap_kp->cols; col++) {
+		omap_writew(~(1 << col) & 0xff,
+			    OMAP1_MPUIO_BASE + OMAP_MPUIO_KBC);
+
+		udelay(omap_kp->delay);
+
+		state[col] = ~omap_readw(OMAP1_MPUIO_BASE +
+					 OMAP_MPUIO_KBR_LATCH) & 0xff;
+	}
+	omap_writew(0x00, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBC);
+	udelay(2);
+}
+
+static void omap_kp_tasklet(unsigned long data)
+{
+	struct omap_kp *omap_kp_data = (struct omap_kp *) data;
+	unsigned short *keycodes = omap_kp_data->input->keycode;
+	unsigned int row_shift = get_count_order(omap_kp_data->cols);
+	unsigned char new_state[8], changed, key_down = 0;
+	int col, row;
+
+	/* check for any changes */
+	omap_kp_scan_keypad(omap_kp_data, new_state);
+
+	/* check for changes and print those */
+	for (col = 0; col < omap_kp_data->cols; col++) {
+		changed = new_state[col] ^ keypad_state[col];
+		key_down |= new_state[col];
+		if (changed == 0)
+			continue;
+
+		for (row = 0; row < omap_kp_data->rows; row++) {
+			int key;
+			if (!(changed & (1 << row)))
+				continue;
+#ifdef NEW_BOARD_LEARNING_MODE
+			printk(KERN_INFO "omap-keypad: key %d-%d %s\n", col,
+			       row, (new_state[col] & (1 << row)) ?
+			       "pressed" : "released");
+#else
+			key = keycodes[MATRIX_SCAN_CODE(row, col, row_shift)];
+
+			if (!(kp_cur_group == (key & GROUP_MASK) ||
+			      kp_cur_group == -1))
+				continue;
+
+			kp_cur_group = key & GROUP_MASK;
+			input_report_key(omap_kp_data->input, key & ~GROUP_MASK,
+					 new_state[col] & (1 << row));
+#endif
+		}
+	}
+	input_sync(omap_kp_data->input);
+	memcpy(keypad_state, new_state, sizeof(keypad_state));
+
+	if (key_down) {
+		/* some key is pressed - keep irq disabled and use timer
+		 * to poll the keypad */
+		mod_timer(&omap_kp_data->timer, jiffies + HZ / 20);
+	} else {
+		/* enable interrupts */
+		omap_writew(0, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+		kp_cur_group = -1;
+	}
+}
+
+static ssize_t omap_kp_enable_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%u\n", kp_enable);
+}
+
+static ssize_t omap_kp_enable_store(struct device *dev, struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	struct omap_kp *omap_kp = dev_get_drvdata(dev);
+	int state;
+
+	if (sscanf(buf, "%u", &state) != 1)
+		return -EINVAL;
+
+	if ((state != 1) && (state != 0))
+		return -EINVAL;
+
+	scoped_guard(mutex, &kp_enable_mutex) {
+		if (state != kp_enable) {
+			if (state)
+				enable_irq(omap_kp->irq);
+			else
+				disable_irq(omap_kp->irq);
+			kp_enable = state;
+		}
+	}
+
+	return strnlen(buf, count);
+}
+
+static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, omap_kp_enable_show, omap_kp_enable_store);
+
+static struct attribute *omap_kp_attrs[] = {
+	&dev_attr_enable.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(omap_kp);
+
+static int omap_kp_probe(struct platform_device *pdev)
+{
+	struct omap_kp *omap_kp;
+	struct input_dev *input_dev;
+	struct omap_kp_platform_data *pdata = dev_get_platdata(&pdev->dev);
+	int ret;
+	unsigned int row_shift, keycodemax;
+
+	if (!pdata->rows || !pdata->cols || !pdata->keymap_data) {
+		printk(KERN_ERR "No rows, cols or keymap_data from pdata\n");
+		return -EINVAL;
+	}
+
+	row_shift = get_count_order(pdata->cols);
+	keycodemax = pdata->rows << row_shift;
+
+	omap_kp = kzalloc_flex(*omap_kp, keymap, keycodemax);
+	input_dev = input_allocate_device();
+	if (!omap_kp || !input_dev) {
+		kfree(omap_kp);
+		input_free_device(input_dev);
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, omap_kp);
+
+	omap_kp->input = input_dev;
+
+	/* Disable the interrupt for the MPUIO keyboard */
+	omap_writew(1, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+
+	if (pdata->delay)
+		omap_kp->delay = pdata->delay;
+
+	omap_kp->rows = pdata->rows;
+	omap_kp->cols = pdata->cols;
+
+	timer_setup(&omap_kp->timer, omap_kp_timer, 0);
+
+	/* get the irq and init timer*/
+	kp_tasklet.data = (unsigned long) omap_kp;
+	tasklet_enable(&kp_tasklet);
+
+	/* setup input device */
+	input_dev->name = "omap-keypad";
+	input_dev->phys = "omap-keypad/input0";
+	input_dev->dev.parent = &pdev->dev;
+
+	input_dev->id.bustype = BUS_HOST;
+	input_dev->id.vendor = 0x0001;
+	input_dev->id.product = 0x0001;
+	input_dev->id.version = 0x0100;
+
+	if (pdata->rep)
+		__set_bit(EV_REP, input_dev->evbit);
+
+	ret = matrix_keypad_build_keymap(pdata->keymap_data, NULL,
+					 pdata->rows, pdata->cols,
+					 omap_kp->keymap, input_dev);
+	if (ret < 0)
+		goto err2;
+
+	ret = input_register_device(omap_kp->input);
+	if (ret < 0) {
+		printk(KERN_ERR "Unable to register omap-keypad input device\n");
+		goto err2;
+	}
+
+	if (pdata->dbounce)
+		omap_writew(0xff, OMAP1_MPUIO_BASE + OMAP_MPUIO_GPIO_DEBOUNCING);
+
+	/* scan current status and enable interrupt */
+	omap_kp_scan_keypad(omap_kp, keypad_state);
+	omap_kp->irq = platform_get_irq(pdev, 0);
+	if (omap_kp->irq >= 0) {
+		if (request_irq(omap_kp->irq, omap_kp_interrupt, 0,
+				"omap-keypad", omap_kp) < 0)
+			goto err3;
+	}
+	omap_writew(0, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+
+	return 0;
+
+err3:
+	input_unregister_device(omap_kp->input);
+	input_dev = NULL;
+err2:
+	kfree(omap_kp);
+	input_free_device(input_dev);
+
+	return -EINVAL;
+}
+
+static void omap_kp_remove(struct platform_device *pdev)
+{
+	struct omap_kp *omap_kp = platform_get_drvdata(pdev);
+
+	/* disable keypad interrupt handling */
+	tasklet_disable(&kp_tasklet);
+	omap_writew(1, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+	free_irq(omap_kp->irq, omap_kp);
+
+	timer_shutdown_sync(&omap_kp->timer);
+	tasklet_kill(&kp_tasklet);
+
+	/* unregister everything */
+	input_unregister_device(omap_kp->input);
+
+	kfree(omap_kp);
+}
+
+static struct platform_driver omap_kp_driver = {
+	.probe		= omap_kp_probe,
+	.remove		= omap_kp_remove,
+	.driver		= {
+		.name	= "omap-keypad",
+		.dev_groups = omap_kp_groups,
+	},
+};
+module_platform_driver(omap_kp_driver);
+
+MODULE_AUTHOR("Timo Teräs");
+MODULE_DESCRIPTION("OMAP Keypad Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:omap-keypad");