{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-38627", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:24.029Z", "datePublished": "2025-08-22T16:00:35.856Z", "dateUpdated": "2026-08-05T12:03:36.334Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:03:36.334Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: compress: fix UAF of f2fs_inode_info in f2fs_free_dic\n\nThe decompress_io_ctx may be released asynchronously after\nI/O completion. If this file is deleted immediately after read,\nand the kworker of processing post_read_wq has not been executed yet\ndue to high workloads, It is possible that the inode(f2fs_inode_info)\nis evicted and freed before it is used f2fs_free_dic.\n\n The UAF case as below:\n Thread A Thread B\n - f2fs_decompress_end_io\n - f2fs_put_dic\n - queue_work\n add free_dic work to post_read_wq\n - do_unlink\n - iput\n - evict\n - call_rcu\n This file is deleted after read.\n\n Thread C kworker to process post_read_wq\n - rcu_do_batch\n - f2fs_free_inode\n - kmem_cache_free\n inode is freed by rcu\n - process_scheduled_works\n - f2fs_late_free_dic\n - f2fs_free_dic\n - f2fs_release_decomp_mem\n read (dic->inode)->i_compress_algorithm\n\nThis patch store compress_algorithm and sbi in dic to avoid inode UAF.\n\nIn addition, the previous solution is deprecated in [1] may cause system hang.\n[1] https://lore.kernel.org/all/c36ab955-c8db-4a8b-a9d0-f07b5f426c3f@kernel.org" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The whole sequence — creating a compressed file via `FS_IOC_SETFLAGS`/`compress_extension`, evicting its page cache with `posix_fadvise()`, reading it, and unlinking it — is performed through ordinary local syscalls on a mounted f2fs volume. No network protocol, remote peer, or adjacent-network data reaches `f2fs_free_dic()`.\nAC:L - The attacker drives both sides of the race: they submit the compressed read that queues `free_work` and they issue the `close()`/`unlink()` that evicts the inode, and they widen the window at will by saturating `post_read_wq` (bounded `max_active = num_online_cpus()`) with concurrent post-read work so the kworker is delayed past the RCU grace period. Every attempt is free and retryable in a loop, and f2fs compression is a mainstream shipping configuration on Android and embedded devices, not a rare option.\nPR:L - No capability, LSM, or namespace gate exists on the path — `vfs_fileattr_set()` only requires `inode_owner_or_capable()` on the attacker's own file, and reading/unlinking a file the attacker created needs nothing beyond normal write access to their own directory. An ordinary user account or an Android app with storage access on a compression-enabled f2fs mount suffices.\nUI:N - The attacking process performs every step itself — create the compressed file, drop its cache, read it, and delete it. No victim must mount a filesystem, open a file, or take any other action.\nS:U - The freed `f2fs_inode_info`, the wild `sbi`/`cops` dereferences, and any resulting corruption all occur within the same kernel's security authority. No hypervisor, IOMMU, guest, or sandbox boundary is crossed.\nC:H - This is a use-after-free read of a `f2fs_inode_cachep` object whose memory the attacker can groom by spraying after the RCU free, so the values pulled out (`inode->i_sb`, `i_compress_algorithm`) are attacker-influenced; the tainted `i_compress_algorithm` byte then indexes the 4-entry `f2fs_cops[]` array up to 255 entries out of bounds, reading arbitrary adjacent kernel data. Combined with the wild `sbi` deref, the flaw yields a kernel-memory read primitive usable for KASLR defeat and data disclosure.\nI:H - The garbage `cops` obtained from the out-of-bounds `f2fs_cops[]` index is immediately used for the indirect call `cops->destroy_decompress_ctx(dic)`, a control-flow hijack primitive, and the wild `sbi` is passed to `page_array_free()` which performs `kmem_cache_free(sbi->page_array_slab, pages)` — freeing a live object into an attacker-influenced cache pointer, a classic path to arbitrary heap corruption and privilege escalation. Per UAF scoring, heap grooming of the recycled inode slab gives write as well as read primitives.\nA:H - Even unexploited, dereferencing the freed inode's `i_sb` and calling through an out-of-bounds `f2fs_cops[]` entry oopses or panics the kernel, and it happens inside a `post_read_wq` kworker so the crash wedges the filesystem's decompression workqueue rather than just one task. The unprivileged attacker can retry the trigger indefinitely, and `panic_on_oops=1` builds (Android, automotive, embedded) take an immediate full system panic." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/f2fs/compress.c", "fs/f2fs/f2fs.h" ], "versions": [ { "version": "bff139b49d9f70c1ac5384aac94554846aa834de", "lessThan": "74cbeeca4f16823ba58c882e1d8b836c0e39c93d", "status": "affected", "versionType": "git" }, { "version": "bff139b49d9f70c1ac5384aac94554846aa834de", "lessThan": "5d604d40cd3232b09cb339941ef958e49283ed0a", "status": "affected", "versionType": "git" }, { "version": "bff139b49d9f70c1ac5384aac94554846aa834de", "lessThan": "cc81768212cdc509e5a986274db7bc24d18cde19", "status": "affected", "versionType": "git" }, { "version": "bff139b49d9f70c1ac5384aac94554846aa834de", "lessThan": "8fae5b6addd5f6895e03797b56e3c7b9f9cd15c9", "status": "affected", "versionType": "git" }, { "version": "bff139b49d9f70c1ac5384aac94554846aa834de", "lessThan": "39868685c2a94a70762bc6d77dc81d781d05bff5", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/f2fs/compress.c", "fs/f2fs/f2fs.h" ], "versions": [ { "version": "6.0", "status": "affected" }, { "version": "0", "lessThan": "6.0", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.175", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.118", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.78", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.1", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.1.175" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.6.118" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.12.78" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.16.1" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.17" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/74cbeeca4f16823ba58c882e1d8b836c0e39c93d" }, { "url": "https://git.kernel.org/stable/c/5d604d40cd3232b09cb339941ef958e49283ed0a" }, { "url": "https://git.kernel.org/stable/c/cc81768212cdc509e5a986274db7bc24d18cde19" }, { "url": "https://git.kernel.org/stable/c/8fae5b6addd5f6895e03797b56e3c7b9f9cd15c9" }, { "url": "https://git.kernel.org/stable/c/39868685c2a94a70762bc6d77dc81d781d05bff5" } ], "title": "f2fs: compress: fix UAF of f2fs_inode_info in f2fs_free_dic", "x_generator": { "engine": "bippy-1.2.0" } } } }