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, 445 insertions, 0 deletions

diff --git a/drivers/char/ps3flash.c b/drivers/char/ps3flash.c
new file mode 100644
index 000000000..c73f44307
--- /dev/null
+++ b/drivers/char/ps3flash.c
@@ -0,0 +1,445 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PS3 FLASH ROM Storage Driver
+ *
+ * Copyright (C) 2007 Sony Computer Entertainment Inc.
+ * Copyright 2007 Sony Corp.
+ */
+
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+
+#include <asm/lv1call.h>
+#include <asm/ps3stor.h>
+
+
+#define DEVICE_NAME		"ps3flash"
+
+#define FLASH_BLOCK_SIZE	(256*1024)
+
+
+struct ps3flash_private {
+	struct mutex mutex;	/* Bounce buffer mutex */
+	u64 chunk_sectors;
+	int tag;		/* Start sector of buffer, -1 if invalid */
+	bool dirty;
+};
+
+static struct ps3_storage_device *ps3flash_dev;
+
+static int ps3flash_read_write_sectors(struct ps3_storage_device *dev,
+				       u64 start_sector, int write)
+{
+	struct ps3flash_private *priv = ps3_system_bus_get_drvdata(&dev->sbd);
+	u64 res = ps3stor_read_write_sectors(dev, dev->bounce_lpar,
+					     start_sector, priv->chunk_sectors,
+					     write);
+	if (res) {
+		dev_err(&dev->sbd.core, "%s:%u: %s failed 0x%llx\n", __func__,
+			__LINE__, write ? "write" : "read", res);
+		return -EIO;
+	}
+	return 0;
+}
+
+static int ps3flash_writeback(struct ps3_storage_device *dev)
+{
+	struct ps3flash_private *priv = ps3_system_bus_get_drvdata(&dev->sbd);
+	int res;
+
+	if (!priv->dirty || priv->tag < 0)
+		return 0;
+
+	res = ps3flash_read_write_sectors(dev, priv->tag, 1);
+	if (res)
+		return res;
+
+	priv->dirty = false;
+	return 0;
+}
+
+static int ps3flash_fetch(struct ps3_storage_device *dev, u64 start_sector)
+{
+	struct ps3flash_private *priv = ps3_system_bus_get_drvdata(&dev->sbd);
+	int res;
+
+	if (start_sector == priv->tag)
+		return 0;
+
+	res = ps3flash_writeback(dev);
+	if (res)
+		return res;
+
+	priv->tag = -1;
+
+	res = ps3flash_read_write_sectors(dev, start_sector, 0);
+	if (res)
+		return res;
+
+	priv->tag = start_sector;
+	return 0;
+}
+
+static loff_t ps3flash_llseek(struct file *file, loff_t offset, int origin)
+{
+	struct ps3_storage_device *dev = ps3flash_dev;
+	return generic_file_llseek_size(file, offset, origin, MAX_LFS_FILESIZE,
+			dev->regions[dev->region_idx].size*dev->blk_size);
+}
+
+static ssize_t ps3flash_read(char __user *userbuf, void *kernelbuf,
+			     size_t count, loff_t *pos)
+{
+	struct ps3_storage_device *dev = ps3flash_dev;
+	struct ps3flash_private *priv = ps3_system_bus_get_drvdata(&dev->sbd);
+	u64 size, sector, offset;
+	int res;
+	size_t remaining, n;
+	const void *src;
+
+	dev_dbg(&dev->sbd.core,
+		"%s:%u: Reading %zu bytes at position %lld to U0x%p/K0x%p\n",
+		__func__, __LINE__, count, *pos, userbuf, kernelbuf);
+
+	size = dev->regions[dev->region_idx].size*dev->blk_size;
+	if (*pos >= size || !count)
+		return 0;
+
+	if (*pos + count > size) {
+		dev_dbg(&dev->sbd.core,
+			"%s:%u Truncating count from %zu to %llu\n", __func__,
+			__LINE__, count, size - *pos);
+		count = size - *pos;
+	}
+
+	sector = *pos / dev->bounce_size * priv->chunk_sectors;
+	offset = *pos % dev->bounce_size;
+
+	remaining = count;
+	do {
+		n = min_t(u64, remaining, dev->bounce_size - offset);
+		src = dev->bounce_buf + offset;
+
+		mutex_lock(&priv->mutex);
+
+		res = ps3flash_fetch(dev, sector);
+		if (res)
+			goto fail;
+
+		dev_dbg(&dev->sbd.core,
+			"%s:%u: copy %lu bytes from 0x%p to U0x%p/K0x%p\n",
+			__func__, __LINE__, n, src, userbuf, kernelbuf);
+		if (userbuf) {
+			if (copy_to_user(userbuf, src, n)) {
+				res = -EFAULT;
+				goto fail;
+			}
+			userbuf += n;
+		}
+		if (kernelbuf) {
+			memcpy(kernelbuf, src, n);
+			kernelbuf += n;
+		}
+
+		mutex_unlock(&priv->mutex);
+
+		*pos += n;
+		remaining -= n;
+		sector += priv->chunk_sectors;
+		offset = 0;
+	} while (remaining > 0);
+
+	return count;
+
+fail:
+	mutex_unlock(&priv->mutex);
+	return res;
+}
+
+static ssize_t ps3flash_write(const char __user *userbuf,
+			      const void *kernelbuf, size_t count, loff_t *pos)
+{
+	struct ps3_storage_device *dev = ps3flash_dev;
+	struct ps3flash_private *priv = ps3_system_bus_get_drvdata(&dev->sbd);
+	u64 size, sector, offset;
+	int res = 0;
+	size_t remaining, n;
+	void *dst;
+
+	dev_dbg(&dev->sbd.core,
+		"%s:%u: Writing %zu bytes at position %lld from U0x%p/K0x%p\n",
+		__func__, __LINE__, count, *pos, userbuf, kernelbuf);
+
+	size = dev->regions[dev->region_idx].size*dev->blk_size;
+	if (*pos >= size || !count)
+		return 0;
+
+	if (*pos + count > size) {
+		dev_dbg(&dev->sbd.core,
+			"%s:%u Truncating count from %zu to %llu\n", __func__,
+			__LINE__, count, size - *pos);
+		count = size - *pos;
+	}
+
+	sector = *pos / dev->bounce_size * priv->chunk_sectors;
+	offset = *pos % dev->bounce_size;
+
+	remaining = count;
+	do {
+		n = min_t(u64, remaining, dev->bounce_size - offset);
+		dst = dev->bounce_buf + offset;
+
+		mutex_lock(&priv->mutex);
+
+		if (n != dev->bounce_size)
+			res = ps3flash_fetch(dev, sector);
+		else if (sector != priv->tag)
+			res = ps3flash_writeback(dev);
+		if (res)
+			goto fail;
+
+		dev_dbg(&dev->sbd.core,
+			"%s:%u: copy %lu bytes from U0x%p/K0x%p to 0x%p\n",
+			__func__, __LINE__, n, userbuf, kernelbuf, dst);
+		if (userbuf) {
+			if (copy_from_user(dst, userbuf, n)) {
+				res = -EFAULT;
+				goto fail;
+			}
+			userbuf += n;
+		}
+		if (kernelbuf) {
+			memcpy(dst, kernelbuf, n);
+			kernelbuf += n;
+		}
+
+		priv->tag = sector;
+		priv->dirty = true;
+
+		mutex_unlock(&priv->mutex);
+
+		*pos += n;
+		remaining -= n;
+		sector += priv->chunk_sectors;
+		offset = 0;
+	} while (remaining > 0);
+
+	return count;
+
+fail:
+	mutex_unlock(&priv->mutex);
+	return res;
+}
+
+static ssize_t ps3flash_user_read(struct file *file, char __user *buf,
+				  size_t count, loff_t *pos)
+{
+	return ps3flash_read(buf, NULL, count, pos);
+}
+
+static ssize_t ps3flash_user_write(struct file *file, const char __user *buf,
+				   size_t count, loff_t *pos)
+{
+	return ps3flash_write(buf, NULL, count, pos);
+}
+
+static ssize_t ps3flash_kernel_read(void *buf, size_t count, loff_t pos)
+{
+	return ps3flash_read(NULL, buf, count, &pos);
+}
+
+static ssize_t ps3flash_kernel_write(const void *buf, size_t count,
+				     loff_t pos)
+{
+	ssize_t res;
+	int wb;
+
+	res = ps3flash_write(NULL, buf, count, &pos);
+	if (res < 0)
+		return res;
+
+	/* Make kernel writes synchronous */
+	wb = ps3flash_writeback(ps3flash_dev);
+	if (wb)
+		return wb;
+
+	return res;
+}
+
+static int ps3flash_flush(struct file *file, fl_owner_t id)
+{
+	return ps3flash_writeback(ps3flash_dev);
+}
+
+static int ps3flash_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+	struct inode *inode = file_inode(file);
+	int err;
+	inode_lock(inode);
+	err = ps3flash_writeback(ps3flash_dev);
+	inode_unlock(inode);
+	return err;
+}
+
+static irqreturn_t ps3flash_interrupt(int irq, void *data)
+{
+	struct ps3_storage_device *dev = data;
+	int res;
+	u64 tag, status;
+
+	res = lv1_storage_get_async_status(dev->sbd.dev_id, &tag, &status);
+
+	if (tag != dev->tag)
+		dev_err(&dev->sbd.core,
+			"%s:%u: tag mismatch, got %llx, expected %llx\n",
+			__func__, __LINE__, tag, dev->tag);
+
+	if (res) {
+		dev_err(&dev->sbd.core, "%s:%u: res=%d status=0x%llx\n",
+			__func__, __LINE__, res, status);
+	} else {
+		dev->lv1_status = status;
+		complete(&dev->done);
+	}
+	return IRQ_HANDLED;
+}
+
+static const struct file_operations ps3flash_fops = {
+	.owner	= THIS_MODULE,
+	.llseek	= ps3flash_llseek,
+	.read	= ps3flash_user_read,
+	.write	= ps3flash_user_write,
+	.flush	= ps3flash_flush,
+	.fsync	= ps3flash_fsync,
+};
+
+static const struct ps3_os_area_flash_ops ps3flash_kernel_ops = {
+	.read	= ps3flash_kernel_read,
+	.write	= ps3flash_kernel_write,
+};
+
+static struct miscdevice ps3flash_misc = {
+	.minor	= MISC_DYNAMIC_MINOR,
+	.name	= DEVICE_NAME,
+	.fops	= &ps3flash_fops,
+};
+
+static int ps3flash_probe(struct ps3_system_bus_device *_dev)
+{
+	struct ps3_storage_device *dev = to_ps3_storage_device(&_dev->core);
+	struct ps3flash_private *priv;
+	int error;
+	unsigned long tmp;
+
+	tmp = dev->regions[dev->region_idx].start*dev->blk_size;
+	if (tmp % FLASH_BLOCK_SIZE) {
+		dev_err(&dev->sbd.core,
+			"%s:%u region start %lu is not aligned\n", __func__,
+			__LINE__, tmp);
+		return -EINVAL;
+	}
+	tmp = dev->regions[dev->region_idx].size*dev->blk_size;
+	if (tmp % FLASH_BLOCK_SIZE) {
+		dev_err(&dev->sbd.core,
+			"%s:%u region size %lu is not aligned\n", __func__,
+			__LINE__, tmp);
+		return -EINVAL;
+	}
+
+	/* use static buffer, kmalloc cannot allocate 256 KiB */
+	if (!ps3flash_bounce_buffer.address)
+		return -ENODEV;
+
+	if (ps3flash_dev) {
+		dev_err(&dev->sbd.core,
+			"Only one FLASH device is supported\n");
+		return -EBUSY;
+	}
+
+	ps3flash_dev = dev;
+
+	priv = kzalloc_obj(*priv);
+	if (!priv) {
+		error = -ENOMEM;
+		goto fail;
+	}
+
+	ps3_system_bus_set_drvdata(&dev->sbd, priv);
+	mutex_init(&priv->mutex);
+	priv->tag = -1;
+
+	dev->bounce_size = ps3flash_bounce_buffer.size;
+	dev->bounce_buf = ps3flash_bounce_buffer.address;
+	priv->chunk_sectors = dev->bounce_size / dev->blk_size;
+
+	error = ps3stor_setup(dev, ps3flash_interrupt);
+	if (error)
+		goto fail_free_priv;
+
+	ps3flash_misc.parent = &dev->sbd.core;
+	error = misc_register(&ps3flash_misc);
+	if (error) {
+		dev_err(&dev->sbd.core, "%s:%u: misc_register failed %d\n",
+			__func__, __LINE__, error);
+		goto fail_teardown;
+	}
+
+	dev_info(&dev->sbd.core, "%s:%u: registered misc device %d\n",
+		 __func__, __LINE__, ps3flash_misc.minor);
+
+	ps3_os_area_flash_register(&ps3flash_kernel_ops);
+	return 0;
+
+fail_teardown:
+	ps3stor_teardown(dev);
+fail_free_priv:
+	kfree(priv);
+	ps3_system_bus_set_drvdata(&dev->sbd, NULL);
+fail:
+	ps3flash_dev = NULL;
+	return error;
+}
+
+static void ps3flash_remove(struct ps3_system_bus_device *_dev)
+{
+	struct ps3_storage_device *dev = to_ps3_storage_device(&_dev->core);
+
+	ps3_os_area_flash_register(NULL);
+	misc_deregister(&ps3flash_misc);
+	ps3stor_teardown(dev);
+	kfree(ps3_system_bus_get_drvdata(&dev->sbd));
+	ps3_system_bus_set_drvdata(&dev->sbd, NULL);
+	ps3flash_dev = NULL;
+}
+
+
+static struct ps3_system_bus_driver ps3flash = {
+	.match_id	= PS3_MATCH_ID_STOR_FLASH,
+	.core.name	= DEVICE_NAME,
+	.core.owner	= THIS_MODULE,
+	.probe		= ps3flash_probe,
+	.remove		= ps3flash_remove,
+	.shutdown	= ps3flash_remove,
+};
+
+
+static int __init ps3flash_init(void)
+{
+	return ps3_system_bus_driver_register(&ps3flash);
+}
+
+static void __exit ps3flash_exit(void)
+{
+	ps3_system_bus_driver_unregister(&ps3flash);
+}
+
+module_init(ps3flash_init);
+module_exit(ps3flash_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("PS3 FLASH ROM Storage Driver");
+MODULE_AUTHOR("Sony Corporation");
+MODULE_ALIAS(PS3_MODULE_ALIAS_STOR_FLASH);