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, 294 insertions, 0 deletions

diff --git a/drivers/ata/libata-zpodd.c b/drivers/ata/libata-zpodd.c
new file mode 100644
index 000000000..414e7c63b
--- /dev/null
+++ b/drivers/ata/libata-zpodd.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/libata.h>
+#include <linux/cdrom.h>
+#include <linux/pm_runtime.h>
+#include <linux/module.h>
+#include <linux/pm_qos.h>
+#include <scsi/scsi_device.h>
+
+#include "libata.h"
+
+static int zpodd_poweroff_delay = 30; /* 30 seconds for power off delay */
+module_param(zpodd_poweroff_delay, int, 0644);
+MODULE_PARM_DESC(zpodd_poweroff_delay, "Poweroff delay for ZPODD in seconds");
+
+enum odd_mech_type {
+	ODD_MECH_TYPE_SLOT,
+	ODD_MECH_TYPE_DRAWER,
+	ODD_MECH_TYPE_UNSUPPORTED,
+};
+
+struct zpodd {
+	enum odd_mech_type	mech_type; /* init during probe, RO afterwards */
+	struct ata_device	*dev;
+
+	/* The following fields are synchronized by PM core. */
+	bool			from_notify; /* resumed as a result of
+					      * acpi wake notification */
+	bool			zp_ready; /* ZP ready state */
+	unsigned long		last_ready; /* last ZP ready timestamp */
+	bool			zp_sampled; /* ZP ready state sampled */
+	bool			powered_off; /* ODD is powered off
+					      *	during suspend */
+};
+
+static int eject_tray(struct ata_device *dev)
+{
+	struct ata_taskfile tf;
+	static const char cdb[ATAPI_CDB_LEN] = {  GPCMD_START_STOP_UNIT,
+		0, 0, 0,
+		0x02,     /* LoEj */
+		0, 0, 0, 0, 0, 0, 0,
+	};
+
+	ata_tf_init(dev, &tf);
+	tf.flags = ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+	tf.command = ATA_CMD_PACKET;
+	tf.protocol = ATAPI_PROT_NODATA;
+
+	return ata_exec_internal(dev, &tf, cdb, DMA_NONE, NULL, 0, 0);
+}
+
+/* Per the spec, only slot type and drawer type ODD can be supported */
+static enum odd_mech_type zpodd_get_mech_type(struct ata_device *dev)
+{
+	char *buf;
+	unsigned int ret;
+	struct rm_feature_desc *desc;
+	struct ata_taskfile tf;
+	static const char cdb[ATAPI_CDB_LEN] = {  GPCMD_GET_CONFIGURATION,
+			2,      /* only 1 feature descriptor requested */
+			0, 3,   /* 3, removable medium feature */
+			0, 0, 0,/* reserved */
+			0, 16,
+			0, 0, 0,
+	};
+
+	buf = kzalloc(16, GFP_KERNEL);
+	if (!buf)
+		return ODD_MECH_TYPE_UNSUPPORTED;
+	desc = (void *)(buf + 8);
+
+	ata_tf_init(dev, &tf);
+	tf.flags = ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+	tf.command = ATA_CMD_PACKET;
+	tf.protocol = ATAPI_PROT_PIO;
+	tf.lbam = 16;
+
+	ret = ata_exec_internal(dev, &tf, cdb, DMA_FROM_DEVICE,
+				buf, 16, 0);
+	if (ret) {
+		kfree(buf);
+		return ODD_MECH_TYPE_UNSUPPORTED;
+	}
+
+	if (be16_to_cpu(desc->feature_code) != 3) {
+		kfree(buf);
+		return ODD_MECH_TYPE_UNSUPPORTED;
+	}
+
+	if (desc->mech_type == 0 && desc->load == 0 && desc->eject == 1) {
+		kfree(buf);
+		return ODD_MECH_TYPE_SLOT;
+	} else if (desc->mech_type == 1 && desc->load == 0 &&
+		   desc->eject == 1) {
+		kfree(buf);
+		return ODD_MECH_TYPE_DRAWER;
+	} else {
+		kfree(buf);
+		return ODD_MECH_TYPE_UNSUPPORTED;
+	}
+}
+
+/* Test if ODD is zero power ready by sense code */
+static bool zpready(struct ata_device *dev)
+{
+	u8 sense_key, *sense_buf;
+	unsigned int ret, asc, ascq, add_len;
+	struct zpodd *zpodd = dev->zpodd;
+
+	ret = atapi_eh_tur(dev, &sense_key);
+
+	if (!ret || sense_key != NOT_READY)
+		return false;
+
+	sense_buf = dev->sector_buf;
+	ret = atapi_eh_request_sense(dev, sense_buf, sense_key);
+	if (ret)
+		return false;
+
+	/* sense valid */
+	if ((sense_buf[0] & 0x7f) != 0x70)
+		return false;
+
+	add_len = sense_buf[7];
+	/* has asc and ascq */
+	if (add_len < 6)
+		return false;
+
+	asc = sense_buf[12];
+	ascq = sense_buf[13];
+
+	if (zpodd->mech_type == ODD_MECH_TYPE_SLOT)
+		/* no media inside */
+		return asc == 0x3a;
+	else
+		/* no media inside and door closed */
+		return asc == 0x3a && ascq == 0x01;
+}
+
+/*
+ * Update the zpodd->zp_ready field. This field will only be set
+ * if the ODD has stayed in ZP ready state for zpodd_poweroff_delay
+ * time, and will be used to decide if power off is allowed. If it
+ * is set, it will be cleared during resume from powered off state.
+ */
+void zpodd_on_suspend(struct ata_device *dev)
+{
+	struct zpodd *zpodd = dev->zpodd;
+	unsigned long expires;
+
+	if (!zpready(dev)) {
+		zpodd->zp_sampled = false;
+		zpodd->zp_ready = false;
+		return;
+	}
+
+	if (!zpodd->zp_sampled) {
+		zpodd->zp_sampled = true;
+		zpodd->last_ready = jiffies;
+		return;
+	}
+
+	expires = zpodd->last_ready + secs_to_jiffies(zpodd_poweroff_delay);
+	if (time_before(jiffies, expires))
+		return;
+
+	zpodd->zp_ready = true;
+}
+
+bool zpodd_zpready(struct ata_device *dev)
+{
+	struct zpodd *zpodd = dev->zpodd;
+	return zpodd->zp_ready;
+}
+
+/*
+ * Enable runtime wake capability through ACPI and set the powered_off flag,
+ * this flag will be used during resume to decide what operations are needed
+ * to take.
+ *
+ * Also, media poll needs to be silenced, so that it doesn't bring the ODD
+ * back to full power state every few seconds.
+ */
+void zpodd_enable_run_wake(struct ata_device *dev)
+{
+	struct zpodd *zpodd = dev->zpodd;
+
+	sdev_disable_disk_events(dev->sdev);
+
+	zpodd->powered_off = true;
+	acpi_pm_set_device_wakeup(&dev->tdev, true);
+}
+
+/* Disable runtime wake capability if it is enabled */
+void zpodd_disable_run_wake(struct ata_device *dev)
+{
+	struct zpodd *zpodd = dev->zpodd;
+
+	if (zpodd->powered_off)
+		acpi_pm_set_device_wakeup(&dev->tdev, false);
+}
+
+/*
+ * Post power on processing after the ODD has been recovered. If the
+ * ODD wasn't powered off during suspend, it doesn't do anything.
+ *
+ * For drawer type ODD, if it is powered on due to user pressed the
+ * eject button, the tray needs to be ejected. This can only be done
+ * after the ODD has been recovered, i.e. link is initialized and
+ * device is able to process NON_DATA PIO command, as eject needs to
+ * send command for the ODD to process.
+ *
+ * The from_notify flag set in wake notification handler function
+ * zpodd_wake_dev represents if power on is due to user's action.
+ *
+ * For both types of ODD, several fields need to be reset.
+ */
+void zpodd_post_poweron(struct ata_device *dev)
+{
+	struct zpodd *zpodd = dev->zpodd;
+
+	if (!zpodd->powered_off)
+		return;
+
+	zpodd->powered_off = false;
+
+	if (zpodd->from_notify) {
+		zpodd->from_notify = false;
+		if (zpodd->mech_type == ODD_MECH_TYPE_DRAWER)
+			eject_tray(dev);
+	}
+
+	zpodd->zp_sampled = false;
+	zpodd->zp_ready = false;
+
+	sdev_enable_disk_events(dev->sdev);
+}
+
+static void zpodd_wake_dev(acpi_handle handle, u32 event, void *context)
+{
+	struct ata_device *ata_dev = context;
+	struct zpodd *zpodd = ata_dev->zpodd;
+	struct device *dev = &ata_dev->sdev->sdev_gendev;
+
+	if (event == ACPI_NOTIFY_DEVICE_WAKE && pm_runtime_suspended(dev)) {
+		zpodd->from_notify = true;
+		pm_runtime_resume(dev);
+	}
+}
+
+static void ata_acpi_add_pm_notifier(struct ata_device *dev)
+{
+	acpi_handle handle = ata_dev_acpi_handle(dev);
+	acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
+				    zpodd_wake_dev, dev);
+}
+
+static void ata_acpi_remove_pm_notifier(struct ata_device *dev)
+{
+	acpi_handle handle = ata_dev_acpi_handle(dev);
+	acpi_remove_notify_handler(handle, ACPI_SYSTEM_NOTIFY, zpodd_wake_dev);
+}
+
+void zpodd_init(struct ata_device *dev)
+{
+	struct acpi_device *adev = ACPI_COMPANION(&dev->tdev);
+	enum odd_mech_type mech_type;
+	struct zpodd *zpodd;
+
+	if (dev->zpodd || !adev || !acpi_device_can_poweroff(adev))
+		return;
+
+	mech_type = zpodd_get_mech_type(dev);
+	if (mech_type == ODD_MECH_TYPE_UNSUPPORTED)
+		return;
+
+	zpodd = kzalloc_obj(struct zpodd);
+	if (!zpodd)
+		return;
+
+	zpodd->mech_type = mech_type;
+
+	ata_acpi_add_pm_notifier(dev);
+	zpodd->dev = dev;
+	dev->zpodd = zpodd;
+	dev_pm_qos_expose_flags(&dev->tdev, 0);
+}
+
+void zpodd_exit(struct ata_device *dev)
+{
+	ata_acpi_remove_pm_notifier(dev);
+	kfree(dev->zpodd);
+	dev->zpodd = NULL;
+}