CVE-2026-63817

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux6ce19aff0b8cd386860855185c6cd79337fc4d2b < 29115b8c9172d34e67ab26cc4f6c209b7a236d7aaffected
LinuxLinux6ce19aff0b8cd386860855185c6cd79337fc4d2b < 13e4b59d3a9413f66f116fa6c4828519b960a5eaaffected
LinuxLinux6ce19aff0b8cd386860855185c6cd79337fc4d2b < 16161444c30d8dff9428abbae42b72ce4e32a932affected
LinuxLinux6ce19aff0b8cd386860855185c6cd79337fc4d2b < 77f216ff9ce5cde8eed9f6d12707e906dffdc9f7affected
LinuxLinux6ce19aff0b8cd386860855185c6cd79337fc4d2b < 0969926d987bbde9a1aa49da317582ba37095805affected
LinuxLinux6ce19aff0b8cd386860855185c6cd79337fc4d2b < 5073c66a96a9c23c0c2533ed4ed06e42f9021208affected
LinuxLinuxa23706426da9b611be5beae0f3faa260fb453b4eaffected
LinuxLinux5.13.19 < 5.14affected
LinuxLinux5.14affected
LinuxLinux0 < 5.14unaffected
LinuxLinux6.1.177 <= 6.1.*unaffected
LinuxLinux6.6.144 <= 6.6.*unaffected
LinuxLinux6.12.95 <= 6.12.*unaffected
LinuxLinux6.18.38 <= 6.18.*unaffected
LinuxLinux7.1.3 <= 7.1.*unaffected
LinuxLinux7.2-rc1 <= *unaffected

Weaknesses

References