CVE-2024-53233 - Resolved Linux Kernel Unicode Vulnerability: Fix utf8_load() Error Path

A vulnerability was discovered and fixed in the Linux kernel, specifically in the unicode component. The vulnerability is related to the error path in the utf8_load() function, causing a kernel bug. This post includes a code snippet showcasing the issue, alongside links to original references, and details about the exploit and its solution. Using simple American English, the following text explains the issue and its resolution in an exclusive manner.

Details

The utf8_load() function in the Linux kernel is responsible for requesting the "utf8_data_table" symbol and then checking if the requested UTF-8 version is supported. If the version is unsupported, it tries to put the data table using symbol_put(). However, when an unsupported version is requested, symbol_put() fails with a kernel bug as demonstrated in the following code snippet:

 kernel BUG at kernel/module/main.c:786!
 RIP: 001:__symbol_put+x93/xb
 Call Trace:
  <TASK>
  ? __die_body.cold+x19/x27
  ? die+x2e/x50
  ? do_trap+xca/x110
  ? do_error_trap+x65/x80
  ? __symbol_put+x93/xb
  ? exc_invalid_op+x51/x70
  ? __symbol_put+x93/xb
  ? asm_exc_invalid_op+x1a/x20
  ? __pfx_cmp_name+x10/x10
  ? __symbol_put+x93/xb
  ? __symbol_put+x62/xb
  utf8_load+xf8/x150

The failure occurs because symbol_put() expects a unique string that identifies the symbol, rather than a pointer to the loaded symbol. To fix this issue, the unique string should be used instead of a pointer.

Resolution

The vulnerability has been resolved by changing the code in utf8_load() to use the correct unique string for symbol identification. This change prevents the kernel bug from appearing when an unsupported version is requested, ensuring stability and correct behavior in the Linux kernel's unicode handling.

For more information about the vulnerability and the fix, please refer to the following sources

- Original Patch Submission
- Linux Kernel Mailing List (LKML) discussion

Conclusion

In summary, CVE-2024-53233 is a vulnerability found in the Linux kernel's unicode component, affecting the utf8_load() function. The issue was caused by the incorrect usage of a pointer instead of a unique string in symbol_put(). By updating the code to utilize the proper unique string, the vulnerability has been resolved, providing a more stable and secure kernel for users worldwide.

Timeline

Published on: 12/27/2024 14:15:31 UTC
Last modified on: 01/20/2025 06:21:45 UTC