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CVE Record

CVE-2025-38627: f2fs: compress: fix UAF of f2fs_inode_info in f2fs_free_dic

In the Linux kernel, the following vulnerability has been resolved: f2fs: compress: fix UAF of f2fs_inode_info in f2fs_free_dic The decompress_io_ctx may be released asynchronously after I/O completion. If this file is deleted immediately after read, and the kworker of processing post_read_wq has not been executed yet due to high workloads, It is possible that the inode(f2fs_inode_info) is evicted and freed before it is used f2fs_free_dic. The UAF case as below: Thread A Thread B - f2fs_decompress_end_io - f2fs_put_dic - queue_work add free_dic work to post_read_wq - do_unlink - iput - evict - call_rcu This file is deleted after read. Thread C kworker to process post_read_wq - rcu_do_batch - f2fs_free_inode - kmem_cache_free inode is freed by rcu - process_scheduled_works - f2fs_late_free_dic - f2fs_free_dic - f2fs_release_decomp_mem read (dic->inode)->i_compress_algorithm This patch store compress_algorithm and sbi in dic to avoid inode UAF. In addition, the previous solution is deprecated in [1] may cause system hang. [1] https://lore.kernel.org/all/c36ab955-c8db-4a8b-a9d0-f07b5f426c3f@kernel.org

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2025-38627 is a Linux kernel memory-safety flaw in F2FS compression cleanup. Under specific timing, a file inode can be freed before delayed decompression cleanup reads it, creating a use-after-free condition. The public bundle does not provide CVSS, proven impact, or active exploitation evidence.

Executive priority

Treat this as a targeted kernel maintenance item, not an emergency based on current evidence. Prioritize patch validation where F2FS compression is used, especially on fleets that process untrusted local files or shared storage workloads.

Technical view

The issue is in F2FS compressed read cleanup. decompress_io_ctx may be released asynchronously after I/O completion, while unlink and inode eviction can free f2fs_inode_info before f2fs_free_dic later references dic->inode. The fix stores compress_algorithm and sbi in the decompression context to avoid dereferencing the freed inode.

Likely exposure

Exposure is likely limited to Linux systems using F2FS with compression paths reachable. The bundle lists Linux kernel versions and stable fix references, but does not provide distribution package status, configuration prerequisites, or cloud image impact.

Exploitation context

The source describes a race involving compressed reads, immediate file deletion, delayed post_read_wq processing, and RCU inode freeing. KEV is false in the provided bundle, and no cited source claims exploitation in the wild.

Researcher notes

Evidence supports a use-after-free race in F2FS decompression cleanup, but not exploitability, privilege impact, or attacker prerequisites. Analysis should focus on affected kernel lineage, F2FS compression enablement, and whether downstream kernels backported the stable fix.

Mitigation direction

  • Check vendor or distribution advisories for fixed kernel packages.
  • Update affected kernels to builds containing the referenced stable fixes.
  • Prioritize systems using F2FS compression or Android-like storage profiles.
  • If patching is delayed, review whether F2FS compression is enabled and exposed.
  • Avoid direct wrangler or deployment assumptions; follow normal kernel change control.

Validation and detection

  • Inventory running kernel versions and F2FS filesystem usage.
  • Confirm whether F2FS compression is enabled on relevant volumes.
  • Verify the deployed kernel includes the referenced upstream stable commit.
  • Check distribution security trackers for backported fixes.
  • Monitor kernel logs for unexplained F2FS or memory-safety faults.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2025-38627 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
6Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxbff139b49d9f70c1ac5384aac94554846aa834de, bff139b49d9f70c1ac5384aac94554846aa834de, bff139b49d9f70c1ac5384aac94554846aa834de, bff139b49d9f70c1ac5384aac94554846aa834de, bff139b49d9f70c1ac5384aac94554846aa834deunaffected
LinuxLinux6.0, 0, 6.1.175, 6.6.118, 6.12.78, 6.16.1, 6.17affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.