CVE-2022-49428 is a vulnerability in the Linux kernel's F2FS (Flash-Friendly File System) implementation. The flaw arises from improper handling of special files (character, block, fifo, or socket files) within the F2FS filesystem. Specifically, the vulnerability is due to the failure to assign the address space operations pointer array for the mapping->a_ops field for these special files. When a specially crafted (fuzzed) image containing the inline_dots flag set on a special file is mounted, the kernel's lookup process triggers a NULL pointer dereference during the __recover_dot_dentries() function call. This occurs because f2fs_add_regular_entry() attempts to invoke a_ops->set_dirty_page(), but since a_ops is NULL, it results in a kernel panic. The vulnerability can be triggered by mounting a maliciously crafted image and performing a directory listing (ls) on the mount point, causing a denial of service (DoS) via kernel panic. The root cause is a missing sanity check on the inline_dots inode in the F2FS code path. This vulnerability affects Linux kernel versions containing the specified commit hash (510022a85839a8409d1e6a519bb86ce71a84f30a) and was publicly disclosed on 2025-02-26. No known exploits are reported in the wild as of now, and no CVSS score has been assigned. The vulnerability is significant because it can cause system crashes, impacting availability and potentially leading to service disruption on affected Linux systems using F2FS.

For European organizations, the impact of CVE-2022-49428 primarily involves availability disruption due to kernel panics triggered by mounting specially crafted F2FS images. Organizations relying on Linux systems with F2FS, especially those using flash storage devices or embedded systems where F2FS is common, may experience unexpected system crashes leading to downtime. This can affect cloud service providers, data centers, telecom infrastructure, and embedded device manufacturers prevalent in Europe. While the vulnerability does not directly expose confidentiality or integrity risks, the denial of service could interrupt critical services, leading to operational and financial impacts. Additionally, if exploited in multi-tenant environments, it could be used to disrupt other tenants' workloads. Since exploitation requires mounting a malicious image and triggering a directory listing, attackers would need some level of access to the system or the ability to persuade users to mount malicious media, which may limit remote exploitation but does not eliminate insider or supply chain risks. The lack of known exploits reduces immediate risk, but the vulnerability should be addressed promptly to prevent future exploitation.

1. Apply the official Linux kernel patches that fix the inline_dots inode sanity check in F2FS as soon as they become available from trusted Linux distributions or kernel maintainers. 2. Restrict mounting of untrusted or unknown F2FS images, especially from external or removable media, to reduce exposure to crafted malicious images. 3. Implement strict access controls and monitoring on systems that allow mounting of filesystems, ensuring only authorized users can perform such operations. 4. Use filesystem integrity monitoring tools to detect unusual or unauthorized mounting activities. 5. For embedded or specialized devices using F2FS, coordinate with vendors to obtain updated firmware or kernel versions addressing this vulnerability. 6. Employ kernel crash monitoring and automated recovery mechanisms to minimize downtime in case of unexpected panics. 7. Educate system administrators about the risks of mounting untrusted images and encourage best practices for filesystem management. 8. Consider disabling F2FS support if it is not required in the environment to eliminate the attack surface related to this vulnerability.