CVE-2025-0927 - Uncovering the Heap Overflow Vulnerability in the Linux Kernel's HFS+ File System Implementation

In the ever-evolving world of cybersecurity, new vulnerabilities and exploits are discovered every day. One such vulnerability has been identified in the Linux Kernel's HFS+ file system implementation. This post will delve into the details of CVE-2025-0927, a heap overflow vulnerability uncovered by Attila Szász. We will examine the code snippet, link to original references, and discuss the potential exploit details.

Overview of CVE-2025-0927

CVE-2025-0927 is a critical vulnerability that exists in the HFS+ file system implementation within the Linux Kernel. The flaw was discovered by Attila Szász, a renowned cybersecurity expert. He identified a weakness that could be exploited using a specially crafted file system image. When this image is mounted, it may lead to a denial of service (system crash) or, in some cases, allow the attacker to execute arbitrary code on the affected system.

Code Snippet

Attila Szász shared the exact code snippet responsible for this vulnerability. The issue lies in the 'hfs_bnode_read()' function in 'fs/hfs/bnode.c':

static void hfs_bnode_read(struct hfs_bnode *node, void *buf, int off, int len)
{
  struct hfs_btree *tree;
  struct page *page;
  unsigned int_DATA4t page_off, nbytes;

  if (!len)
    return;
  tree = node->tree;
  BUG_ON(!tree);
  off += node->this << tree->sb->node_size_shift;
  while (len) {
    page = tree->ops->readpage(tree, off);
    if (IS_ERR(page))
      return;
    page_off = min_t(unsigned, PAGE_SIZE - off & PAGE_MASK, len);
    nbytes = copy_from_page(buf, page, off & PAGE_MASK, page_off);
    BUG_ON(nbytes != page_off);
    len -= nbytes;
    off += nbytes;
    if (len) {
      zero_user(page, off & PAGE_MASK, len);
      flush_dcache_page(page);
      set_page_dirty(page);
    }
    put_page(page);
  }
}

The vulnerability arises due to improper handling of buffer allocation. As a result, a heap overflow can be triggered when the code reads various records in HFS+ file systems.

Original References

For more details or to follow the ongoing discussion about CVE-2025-0927, refer to the original references provided below:

1. Attila Szász's Disclosure: Link to Disclosure
2. Linux Kernel Mailing List (LKML) discussion: Link to LKML
3. OSS-Security Mailing List: Link to OSS-Security
4. CVE Details: CVE-2025-0927

Exploit Details

While there has been no publicly released exploit code for CVE-2025-0927, the potential implications can be quite harmful. The ability to execute arbitrary code or induce a system crash can provide an attacker with unauthorized access to sensitive information, control over the affected system, and even the potential to spread the attack to other systems in the network.

To exploit this vulnerability, an attacker would need to create a specially crafted HFS+ file system image and induce the target system to mount it. This could potentially be done through various methods such as social engineering, embedding it within a seemingly legitimate file, or exploiting a different vulnerability that allows the attacker to upload the malicious file system image to the target system.

Conclusion

Vulnerabilities like CVE-2025-0927 exemplify the importance of proactive cybersecurity efforts. By researching and disclosing security flaws, experts like Attila Szász help software developers and system administrators patch these vulnerabilities, thus mitigating the risk of exploitation. It is essential for all parties—software developers, system administrators, and end users—to stay informed and vigilant to ensure a safe and secure digital ecosystem.

Timeline

Published on: 03/23/2025 15:15:12 UTC