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, 329 insertions, 0 deletions

diff --git a/drivers/soc/fsl/dpaa2-console.c b/drivers/soc/fsl/dpaa2-console.c
new file mode 100644
index 000000000..7f2ffe38d
--- /dev/null
+++ b/drivers/soc/fsl/dpaa2-console.c
@@ -0,0 +1,329 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
+/*
+ * Freescale DPAA2 Platforms Console Driver
+ *
+ * Copyright 2015-2016 Freescale Semiconductor Inc.
+ * Copyright 2018 NXP
+ */
+
+#define pr_fmt(fmt) "dpaa2-console: " fmt
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/miscdevice.h>
+#include <linux/platform_device.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/io.h>
+
+/* MC firmware base low/high registers indexes */
+#define MCFBALR_OFFSET 0
+#define MCFBAHR_OFFSET 1
+
+/* Bit masks used to get the most/least significant part of the MC base addr */
+#define MC_FW_ADDR_MASK_HIGH 0x1FFFF
+#define MC_FW_ADDR_MASK_LOW  0xE0000000
+
+#define MC_BUFFER_OFFSET 0x01000000
+#define MC_BUFFER_SIZE   (1024 * 1024 * 16)
+#define MC_OFFSET_DELTA  MC_BUFFER_OFFSET
+
+#define AIOP_BUFFER_OFFSET 0x06000000
+#define AIOP_BUFFER_SIZE   (1024 * 1024 * 16)
+#define AIOP_OFFSET_DELTA  0
+
+#define LOG_HEADER_FLAG_BUFFER_WRAPAROUND 0x80000000
+#define LAST_BYTE(a) ((a) & ~(LOG_HEADER_FLAG_BUFFER_WRAPAROUND))
+
+/* MC and AIOP Magic words */
+#define MAGIC_MC   0x4d430100
+#define MAGIC_AIOP 0x41494F50
+
+struct log_header {
+	__le32 magic_word;
+	char reserved[4];
+	__le32 buf_start;
+	__le32 buf_length;
+	__le32 last_byte;
+};
+
+struct console_data {
+	void __iomem *map_addr;
+	struct log_header __iomem *hdr;
+	void __iomem *start_addr;
+	void __iomem *end_addr;
+	void __iomem *end_of_data;
+	void __iomem *cur_ptr;
+};
+
+static struct resource mc_base_addr;
+
+static inline void adjust_end(struct console_data *cd)
+{
+	u32 last_byte = readl(&cd->hdr->last_byte);
+
+	cd->end_of_data = cd->start_addr + LAST_BYTE(last_byte);
+}
+
+static u64 get_mc_fw_base_address(void)
+{
+	u64 mcfwbase = 0ULL;
+	u32 __iomem *mcfbaregs;
+
+	mcfbaregs = ioremap(mc_base_addr.start, resource_size(&mc_base_addr));
+	if (!mcfbaregs) {
+		pr_err("could not map MC Firmware Base registers\n");
+		return 0;
+	}
+
+	mcfwbase  = readl(mcfbaregs + MCFBAHR_OFFSET) &
+			  MC_FW_ADDR_MASK_HIGH;
+	mcfwbase <<= 32;
+	mcfwbase |= readl(mcfbaregs + MCFBALR_OFFSET) & MC_FW_ADDR_MASK_LOW;
+	iounmap(mcfbaregs);
+
+	pr_debug("MC base address at 0x%016llx\n", mcfwbase);
+	return mcfwbase;
+}
+
+static ssize_t dpaa2_console_size(struct console_data *cd)
+{
+	ssize_t size;
+
+	if (cd->cur_ptr <= cd->end_of_data)
+		size = cd->end_of_data - cd->cur_ptr;
+	else
+		size = (cd->end_addr - cd->cur_ptr) +
+			(cd->end_of_data - cd->start_addr);
+
+	return size;
+}
+
+static int dpaa2_generic_console_open(struct inode *node, struct file *fp,
+				      u64 offset, u64 size,
+				      u32 expected_magic,
+				      u32 offset_delta)
+{
+	u32 read_magic, wrapped, last_byte, buf_start, buf_length;
+	struct console_data *cd;
+	u64 base_addr;
+	int err;
+
+	cd = kmalloc_obj(*cd);
+	if (!cd)
+		return -ENOMEM;
+
+	base_addr = get_mc_fw_base_address();
+	if (!base_addr) {
+		err = -EIO;
+		goto err_fwba;
+	}
+
+	cd->map_addr = ioremap(base_addr + offset, size);
+	if (!cd->map_addr) {
+		pr_err("cannot map console log memory\n");
+		err = -EIO;
+		goto err_ioremap;
+	}
+
+	cd->hdr = (struct log_header __iomem *)cd->map_addr;
+	read_magic = readl(&cd->hdr->magic_word);
+	last_byte =  readl(&cd->hdr->last_byte);
+	buf_start =  readl(&cd->hdr->buf_start);
+	buf_length = readl(&cd->hdr->buf_length);
+
+	if (read_magic != expected_magic) {
+		pr_warn("expected = %08x, read = %08x\n",
+			expected_magic, read_magic);
+		err = -EIO;
+		goto err_magic;
+	}
+
+	cd->start_addr = cd->map_addr + buf_start - offset_delta;
+	cd->end_addr = cd->start_addr + buf_length;
+
+	wrapped = last_byte & LOG_HEADER_FLAG_BUFFER_WRAPAROUND;
+
+	adjust_end(cd);
+	if (wrapped && cd->end_of_data != cd->end_addr)
+		cd->cur_ptr = cd->end_of_data + 1;
+	else
+		cd->cur_ptr = cd->start_addr;
+
+	fp->private_data = cd;
+
+	return 0;
+
+err_magic:
+	iounmap(cd->map_addr);
+
+err_ioremap:
+err_fwba:
+	kfree(cd);
+
+	return err;
+}
+
+static int dpaa2_mc_console_open(struct inode *node, struct file *fp)
+{
+	return dpaa2_generic_console_open(node, fp,
+					  MC_BUFFER_OFFSET, MC_BUFFER_SIZE,
+					  MAGIC_MC, MC_OFFSET_DELTA);
+}
+
+static int dpaa2_aiop_console_open(struct inode *node, struct file *fp)
+{
+	return dpaa2_generic_console_open(node, fp,
+					  AIOP_BUFFER_OFFSET, AIOP_BUFFER_SIZE,
+					  MAGIC_AIOP, AIOP_OFFSET_DELTA);
+}
+
+static int dpaa2_console_close(struct inode *node, struct file *fp)
+{
+	struct console_data *cd = fp->private_data;
+
+	iounmap(cd->map_addr);
+	kfree(cd);
+	return 0;
+}
+
+static ssize_t dpaa2_console_read(struct file *fp, char __user *buf,
+				  size_t count, loff_t *f_pos)
+{
+	struct console_data *cd = fp->private_data;
+	size_t bytes = dpaa2_console_size(cd);
+	size_t bytes_end = cd->end_addr - cd->cur_ptr;
+	size_t written = 0;
+	void *kbuf;
+	int err;
+
+	/* Check if we need to adjust the end of data addr */
+	adjust_end(cd);
+
+	if (cd->end_of_data == cd->cur_ptr)
+		return 0;
+
+	if (count < bytes)
+		bytes = count;
+
+	kbuf = kmalloc(bytes, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	if (bytes > bytes_end) {
+		memcpy_fromio(kbuf, cd->cur_ptr, bytes_end);
+		if (copy_to_user(buf, kbuf, bytes_end)) {
+			err = -EFAULT;
+			goto err_free_buf;
+		}
+		buf += bytes_end;
+		cd->cur_ptr = cd->start_addr;
+		bytes -= bytes_end;
+		written += bytes_end;
+	}
+
+	memcpy_fromio(kbuf, cd->cur_ptr, bytes);
+	if (copy_to_user(buf, kbuf, bytes)) {
+		err = -EFAULT;
+		goto err_free_buf;
+	}
+	cd->cur_ptr += bytes;
+	written += bytes;
+
+	kfree(kbuf);
+	return written;
+
+err_free_buf:
+	kfree(kbuf);
+
+	return err;
+}
+
+static const struct file_operations dpaa2_mc_console_fops = {
+	.owner          = THIS_MODULE,
+	.open           = dpaa2_mc_console_open,
+	.release        = dpaa2_console_close,
+	.read           = dpaa2_console_read,
+};
+
+static struct miscdevice dpaa2_mc_console_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "dpaa2_mc_console",
+	.fops = &dpaa2_mc_console_fops
+};
+
+static const struct file_operations dpaa2_aiop_console_fops = {
+	.owner          = THIS_MODULE,
+	.open           = dpaa2_aiop_console_open,
+	.release        = dpaa2_console_close,
+	.read           = dpaa2_console_read,
+};
+
+static struct miscdevice dpaa2_aiop_console_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "dpaa2_aiop_console",
+	.fops = &dpaa2_aiop_console_fops
+};
+
+static int dpaa2_console_probe(struct platform_device *pdev)
+{
+	int error;
+
+	error = of_address_to_resource(pdev->dev.of_node, 0, &mc_base_addr);
+	if (error < 0) {
+		pr_err("of_address_to_resource() failed for %pOF with %d\n",
+		       pdev->dev.of_node, error);
+		return error;
+	}
+
+	error = misc_register(&dpaa2_mc_console_dev);
+	if (error) {
+		pr_err("cannot register device %s\n",
+		       dpaa2_mc_console_dev.name);
+		goto err_register_mc;
+	}
+
+	error = misc_register(&dpaa2_aiop_console_dev);
+	if (error) {
+		pr_err("cannot register device %s\n",
+		       dpaa2_aiop_console_dev.name);
+		goto err_register_aiop;
+	}
+
+	return 0;
+
+err_register_aiop:
+	misc_deregister(&dpaa2_mc_console_dev);
+err_register_mc:
+	return error;
+}
+
+static void dpaa2_console_remove(struct platform_device *pdev)
+{
+	misc_deregister(&dpaa2_mc_console_dev);
+	misc_deregister(&dpaa2_aiop_console_dev);
+}
+
+static const struct of_device_id dpaa2_console_match_table[] = {
+	{ .compatible = "fsl,dpaa2-console",},
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, dpaa2_console_match_table);
+
+static struct platform_driver dpaa2_console_driver = {
+	.driver = {
+		   .name = "dpaa2-console",
+		   .pm = NULL,
+		   .of_match_table = dpaa2_console_match_table,
+		   },
+	.probe = dpaa2_console_probe,
+	.remove = dpaa2_console_remove,
+};
+module_platform_driver(dpaa2_console_driver);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Roy Pledge <roy.pledge@nxp.com>");
+MODULE_DESCRIPTION("DPAA2 console driver");