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

CVE-2025-38627 is fixed in linux on 1 platform, first by DEBIAN-CVE-2025-38627, released August 22, 2025. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2025-38627
- Priority: High
- CVSS: 7.8 (Moderate)
- EPSS: 0.0018
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 22, 2025
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-38627

## Description

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

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.176-1 | [DEBIAN-CVE-2025-38627](https://patchblox.com/security/data/fix/linux/debian-cve-2025-38627.md) | Aug 22, 2025 |
| Linux | linux Debian 13.5 (trixie) | 6.12.85-1 | [DEBIAN-CVE-2025-38627](https://patchblox.com/security/data/fix/linux/debian-cve-2025-38627.md) | Aug 22, 2025 |
| Linux | linux Debian 14 | 6.16.3-1 | [DEBIAN-CVE-2025-38627](https://patchblox.com/security/data/fix/linux/debian-cve-2025-38627.md) | Aug 22, 2025 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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