CVE-2024-25260 - A NULL Pointer Dereference in elfutils v.189: A Deep Dive into handle_verdef() function at readelf.c

A widespread vulnerability in the open-source software package elfutils v.189 was discovered, bearing the label CVE-2024-25260. Elfutils is a collection of utilities and libraries for managing ELF files (Executable and Linkable Format) - the standard format for executable files, shared libraries, and core dumps used in Unix and Unix-like systems. This vulnerability affects any system that uses elfutils, which includes popular operating systems like Linux.

This post aims to provide a detailed look at CVE-2024-25260, with a focus on the NULL pointer dereference in the handle_verdef() function at readelf.c. We will also present a code snippet and provide links to the original references to understand the specifics of the vulnerability and its exploitation.

Exploit Details

CVE-2024-25260 is a NULL pointer dereference, allowing an attacker to crash the system by executing a carefully crafted ELF file. The issue stems from a vulnerability in the handle_verdef() function in readelf.c. Specifically, an improperly handled input triggers a NULL pointer dereference, resulting in a crash.

The handle_verdef() function processes version data present in the ELF files, and the NULL pointer dereference occurs due to inadequate input validation coupled with incorrect error handling. To help better understand the issue, let's examine the handle_verdef() function through a snippet of the vulnerable code:

static int
handle_verdef(struct readelf_ctxt *ctxt)
{
  ...
  // Loop through the version definitions present in the file
  for (uint_fast16_t cnt = ; cnt < shnum; ++cnt)
  {
    ...
    // Populate verdef variable
    GElf_Verdef verdef_mem;
    GElf_Verdef *verdef = gelf_getverdef(data, offset, &verdef_mem);

    // NULL pointer dereference due to inadequate input validation
    if (verdef == NULL)
    {
        // Issue: Previously unhandled NULL pointer dereference
        // Fix: Proper error handling and return error code
        error(, , gettext("cannot get version definition: %s"),
            elf_errmsg(-1));
        return 1;
    }
    ...
  }
  ...
}

This code snippet showcases how the input data from the ELF file is inadequately validated before being utilized within the loop. The vulnerability surfaces when the gelf_getverdef() function attempts to fetch the version definition and returns a NULL value, leading to an unhandled NULL dereference error. The fix for this issue is to introduce proper error handling, which involves checking the return value of gelf_getverdef().

Original References

- CVE-2024-25260 Vulnerability Details
- Elfutils v.189 Commit / Patch

Conclusion

CVE-2024-25260 demonstrates the importance of robust input validation and proper error handling in effectively maintaining the security of widely-used software packages. Users should ensure that their systems are updated with the latest elfutils version to prevent exploitation of this vulnerability. By keeping a watchful eye on similar issues, we can help contribute to a more secure software ecosystem.

Timeline

Published on: 02/20/2024 18:15:52 UTC
Last modified on: 02/20/2024 19:50:53 UTC