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, 190 insertions, 0 deletions

diff --git a/drivers/usb/misc/ehset.c b/drivers/usb/misc/ehset.c
new file mode 100644
index 000000000..36b6e9fa7
--- /dev/null
+++ b/drivers/usb/misc/ehset.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2010-2013, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+#include <linux/usb/ch11.h>
+
+#define TEST_SE0_NAK_PID			0x0101
+#define TEST_J_PID				0x0102
+#define TEST_K_PID				0x0103
+#define TEST_PACKET_PID				0x0104
+#define TEST_HS_HOST_PORT_SUSPEND_RESUME	0x0106
+#define TEST_SINGLE_STEP_GET_DEV_DESC		0x0107
+#define TEST_SINGLE_STEP_SET_FEATURE		0x0108
+
+extern const struct usb_device_id *usb_device_match_id(struct usb_device *udev,
+						const struct usb_device_id *id);
+
+/*
+ * A list of USB hubs which requires to disable the power
+ * to the port before starting the testing procedures.
+ */
+static const struct usb_device_id ehset_hub_list[] = {
+	{ USB_DEVICE(0x0424, 0x4502) },
+	{ USB_DEVICE(0x0424, 0x4913) },
+	{ USB_DEVICE(0x0451, 0x8027) },
+	{ }
+};
+
+static int ehset_prepare_port_for_testing(struct usb_device *hub_udev, u16 portnum)
+{
+	int ret = 0;
+
+	/*
+	 * The USB2.0 spec chapter 11.24.2.13 says that the USB port which is
+	 * going under test needs to be put in suspend before sending the
+	 * test command. Most hubs don't enforce this precondition, but there
+	 * are some hubs which needs to disable the power to the port before
+	 * starting the test.
+	 */
+	if (usb_device_match_id(hub_udev, ehset_hub_list)) {
+		ret = usb_control_msg_send(hub_udev, 0, USB_REQ_CLEAR_FEATURE,
+					   USB_RT_PORT, USB_PORT_FEAT_ENABLE,
+					   portnum, NULL, 0, 1000, GFP_KERNEL);
+		/*
+		 * Wait for the port to be disabled. It's an arbitrary value
+		 * which worked every time.
+		 */
+		msleep(100);
+	} else {
+		/*
+		 * For the hubs which are compliant with the spec,
+		 * put the port in SUSPEND.
+		 */
+		ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
+					   USB_RT_PORT, USB_PORT_FEAT_SUSPEND,
+					   portnum, NULL, 0, 1000, GFP_KERNEL);
+	}
+	return ret;
+}
+
+static int ehset_probe(struct usb_interface *intf,
+		       const struct usb_device_id *id)
+{
+	int ret = -EINVAL;
+	struct usb_device *dev = interface_to_usbdev(intf);
+	struct usb_device *hub_udev = dev->parent;
+	struct usb_device_descriptor buf;
+	u8 portnum = dev->portnum;
+	u16 test_pid = le16_to_cpu(dev->descriptor.idProduct);
+
+	switch (test_pid) {
+	case TEST_SE0_NAK_PID:
+		ret = ehset_prepare_port_for_testing(hub_udev, portnum);
+		if (ret < 0)
+			break;
+		ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
+					   USB_RT_PORT, USB_PORT_FEAT_TEST,
+					   (USB_TEST_SE0_NAK << 8) | portnum,
+					   NULL, 0, 1000, GFP_KERNEL);
+		break;
+	case TEST_J_PID:
+		ret = ehset_prepare_port_for_testing(hub_udev, portnum);
+		if (ret < 0)
+			break;
+		ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
+					   USB_RT_PORT, USB_PORT_FEAT_TEST,
+					   (USB_TEST_J << 8) | portnum, NULL, 0,
+					   1000, GFP_KERNEL);
+		break;
+	case TEST_K_PID:
+		ret = ehset_prepare_port_for_testing(hub_udev, portnum);
+		if (ret < 0)
+			break;
+		ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
+					   USB_RT_PORT, USB_PORT_FEAT_TEST,
+					   (USB_TEST_K << 8) | portnum, NULL, 0,
+					   1000, GFP_KERNEL);
+		break;
+	case TEST_PACKET_PID:
+		ret = ehset_prepare_port_for_testing(hub_udev, portnum);
+		if (ret < 0)
+			break;
+		ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
+					   USB_RT_PORT, USB_PORT_FEAT_TEST,
+					   (USB_TEST_PACKET << 8) | portnum,
+					   NULL, 0, 1000, GFP_KERNEL);
+		break;
+	case TEST_HS_HOST_PORT_SUSPEND_RESUME:
+		/* Test: wait for 15secs -> suspend -> 15secs delay -> resume */
+		msleep(15 * 1000);
+		ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
+					   USB_RT_PORT, USB_PORT_FEAT_SUSPEND,
+					   portnum, NULL, 0, 1000, GFP_KERNEL);
+		if (ret < 0)
+			break;
+
+		msleep(15 * 1000);
+		ret = usb_control_msg_send(hub_udev, 0, USB_REQ_CLEAR_FEATURE,
+					   USB_RT_PORT, USB_PORT_FEAT_SUSPEND,
+					   portnum, NULL, 0, 1000, GFP_KERNEL);
+		break;
+	case TEST_SINGLE_STEP_GET_DEV_DESC:
+		/* Test: wait for 15secs -> GetDescriptor request */
+		msleep(15 * 1000);
+
+		ret = usb_control_msg_recv(dev, 0, USB_REQ_GET_DESCRIPTOR,
+					   USB_DIR_IN, USB_DT_DEVICE << 8, 0,
+					   &buf, USB_DT_DEVICE_SIZE,
+					   USB_CTRL_GET_TIMEOUT, GFP_KERNEL);
+		break;
+	case TEST_SINGLE_STEP_SET_FEATURE:
+		/*
+		 * GetDescriptor SETUP request -> 15secs delay -> IN & STATUS
+		 *
+		 * Note, this test is only supported on root hubs since the
+		 * SetPortFeature handling can only be done inside the HCD's
+		 * hub_control callback function.
+		 */
+		if (hub_udev != dev->bus->root_hub) {
+			dev_err(&intf->dev, "SINGLE_STEP_SET_FEATURE test only supported on root hub\n");
+			break;
+		}
+
+		ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
+					   USB_RT_PORT, USB_PORT_FEAT_TEST,
+					   (6 << 8) | portnum, NULL, 0,
+					   60 * 1000, GFP_KERNEL);
+
+		break;
+	default:
+		dev_err(&intf->dev, "%s: unsupported PID: 0x%x\n",
+			__func__, test_pid);
+	}
+
+	return ret;
+}
+
+static void ehset_disconnect(struct usb_interface *intf)
+{
+}
+
+static const struct usb_device_id ehset_id_table[] = {
+	{ USB_DEVICE(0x1a0a, TEST_SE0_NAK_PID) },
+	{ USB_DEVICE(0x1a0a, TEST_J_PID) },
+	{ USB_DEVICE(0x1a0a, TEST_K_PID) },
+	{ USB_DEVICE(0x1a0a, TEST_PACKET_PID) },
+	{ USB_DEVICE(0x1a0a, TEST_HS_HOST_PORT_SUSPEND_RESUME) },
+	{ USB_DEVICE(0x1a0a, TEST_SINGLE_STEP_GET_DEV_DESC) },
+	{ USB_DEVICE(0x1a0a, TEST_SINGLE_STEP_SET_FEATURE) },
+	{ }			/* Terminating entry */
+};
+MODULE_DEVICE_TABLE(usb, ehset_id_table);
+
+static struct usb_driver ehset_driver = {
+	.name =		"usb_ehset_test",
+	.probe =	ehset_probe,
+	.disconnect =	ehset_disconnect,
+	.id_table =	ehset_id_table,
+};
+
+module_usb_driver(ehset_driver);
+
+MODULE_DESCRIPTION("USB Driver for EHSET Test Fixture");
+MODULE_LICENSE("GPL v2");