HighFix available

f2fs: validate compress cache inode only when enabled

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: f2fs: validate compress cache inode only when enabled F2FS_COMPRESS_INO() uses NM_I(sbi)->max_nid as the synthetic inode number for the compressed page cache inode. That inode only exists when the compress_cache mount option is enabled. When compress_cache is disabled, max_nid is outside the valid inode range. A corrupted directory entry that points to ino == max_nid should therefore be rejected by f2fs_check_nid_range(). However, is_meta_ino() currently treats F2FS_COMPRESS_INO() as a meta inode unconditionally, so f2fs_iget() bypasses do_read_inode() and its nid range check, and instantiates a fake internal inode instead. Gate the compressed cache inode case on COMPRESS_CACHE, matching f2fs_init_compress_inode(). With compress_cache disabled, ino == max_nid now follows the normal inode path and is rejected as an out-of-range nid.

Products: Kernel
Affected versions: Not specified
Fixed versions: 5.15.212, 6.1.177, 6.12.95, 6.18.38, 6.6.144, 7.1.3
CVEs: CVE-2026-63817
Confirmed fixed CVEs: Not specified
Updated in this feed: 28 Oct 2026, 08:57 UTC · Revision 1

Source evidence

f2fs: validate compress cache inode only when enabled

core-osv · Original source

Published 19 Jul 2026, 12:02 UTC

osv:CVE-2026-63817

Kernel

Fixed versions: 5.15.212, 6.1.177, 6.6.144, 6.12.95, 6.18.38, 7.1.3

Complete source record

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  "url": "https://osv.dev/vulnerability/CVE-2026-63817",
  "method": "structured",
  "payload": {
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    "title": "f2fs: validate compress cache inode only when enabled",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: f2fs: validate compress cache inode only when enabled F2FS_COMPRESS_INO() uses NM_I(sbi)->max_nid as the synthetic inode number for the compressed page cache inode. That inode only exists when the compress_cache mount option is enabled. When compress_cache is disabled, max_nid is outside the valid inode range. A corrupted directory entry that points to ino == max_nid should therefore be rejected by f2fs_check_nid_range(). However, is_meta_ino() currently treats F2FS_COMPRESS_INO() as a meta inode unconditionally, so f2fs_iget() bypasses do_read_inode() and its nid range check, and instantiates a fake internal inode instead. Gate the compressed cache inode case on COMPRESS_CACHE, matching f2fs_init_compress_inode(). With compress_cache disabled, ino == max_nid now follows the normal inode path and is rejected as an out-of-range nid.",
    "evidence": "osv:CVE-2026-63817",
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      "modified": "2026-10-08T02:51:28.839184386Z",
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      "references": [
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  "source_id": "core-osv",
  "document_id": 98311,
  "published_at": "2026-07-19T12:02:16.441+00:00"
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