CVE-2026-68148 (GCVE-0-2026-68148)
Vulnerability from cvelistv5
Published
2026-08-10 11:59
Modified
2026-10-19 20:58
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: fscrypt: Add missing superblock check in find_or_insert_direct_key() The legacy 'fscrypt_direct_keys' table caches master keys that are used by v1 encryption policies that have FSCRYPT_POLICY_FLAG_DIRECT_KEY. It's just a global table for all filesystems (since the keys can be provided by the legacy process-subscribed keyrings mechanism, which makes it difficult to reuse super_block::s_master_keys). The entries in it ('struct fscrypt_direct_key') do contain a super_block pointer, though, for passing to fscrypt_destroy_inline_crypt_key() when the last inode that references the key is evicted. However, when finding the fscrypt_direct_key for an inode, we weren't actually comparing the super_block pointer. As a result, inodes with different super_blocks could point to the same fscrypt_direct_key. That could extend the lifetime of a fscrypt_direct_key beyond the super_block it points to, causing a use-after-free later. Fix this by creating distinct fscrypt_direct_key structs for distinct super_block structs. Note that this problem doesn't exist in the v2 policy equivalent ("per-mode keys"), since the data structures there are per super_block.
References
Impacted products
Vendor Product Version
Linux Linux Version: 22e9947a4b2ba255888541bd0111cf00b9b16586
Version: 22e9947a4b2ba255888541bd0111cf00b9b16586
Version: 22e9947a4b2ba255888541bd0111cf00b9b16586
Version: 22e9947a4b2ba255888541bd0111cf00b9b16586
Version: 22e9947a4b2ba255888541bd0111cf00b9b16586
Version: 22e9947a4b2ba255888541bd0111cf00b9b16586
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