CVE-2022-49170 is a vulnerability in the Linux kernel's F2FS (Flash-Friendly File System) implementation. The flaw arises from a missing sanity check on the 'curseg->alloc_type' variable, which leads to an out-of-bounds array access on the 'sbi->block_count[]' array. Specifically, when mounting and operating on a corrupted F2FS image, the kernel can trigger an array-index-out-of-bounds error, as detected by the Undefined Behavior Sanitizer (UBSAN). The issue manifests in the function 'f2fs_allocate_data_block' within the segment.c source file. The vulnerability can cause kernel crashes or panics due to invalid memory access, potentially leading to denial of service (DoS). The root cause is the lack of validation on the allocation type index before it is used to access the block_count array, which can be manipulated by mounting a corrupted or maliciously crafted F2FS image. The vulnerability was identified and reported by Wenqing Liu and affects Linux kernel versions around 5.17-rc4 and 5.17-rc6. The fix involves adding proper sanity checks to prevent out-of-bounds access. No known exploits are reported in the wild, and no CVSS score has been assigned yet.

For European organizations, this vulnerability poses a risk primarily to systems running Linux kernels with vulnerable F2FS implementations, especially those using F2FS on flash storage devices. The impact includes potential denial of service through kernel crashes when mounting or operating on corrupted or malicious F2FS images. This could disrupt critical services, especially in environments relying on Linux-based infrastructure such as cloud providers, telecom operators, and embedded systems in industrial control or IoT devices. While the vulnerability does not directly lead to privilege escalation or data leakage, the resulting system instability could cause operational downtime and impact availability. Organizations using containerized environments or virtual machines with F2FS-backed storage should also consider the risk. Given the lack of known exploits, the immediate threat may be low, but the vulnerability could be leveraged in targeted attacks or combined with other exploits to increase impact.

1. Apply the latest Linux kernel patches that include the fix for CVE-2022-49170 as soon as they become available from trusted sources or distributions. 2. Avoid mounting untrusted or corrupted F2FS images, especially from unknown or unverified sources. 3. Implement strict validation and scanning of file system images before deployment in production environments. 4. Monitor kernel logs for signs of UBSAN or out-of-bounds errors related to F2FS operations to detect potential exploitation attempts. 5. For embedded or specialized devices using F2FS, coordinate with vendors to ensure firmware or kernel updates are applied promptly. 6. Employ kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and Kernel Page Table Isolation (KPTI) to reduce exploitation risk. 7. Use container security best practices to limit the impact of kernel vulnerabilities, including running containers with minimal privileges and resource limits.