fscrypt: Add missing superblock check in find_or_insert_direct_key()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-68148
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-10 13:20:00 UTC
Updated2026-08-19 17:20:32 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000910000 probability, percentile 0.005620000 (date 2026-08-19)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 22e9947a4b2ba255888541bd0111cf00b9b16586 965b5bc8cf5031225e057979ce660fec2bd5fbfc git Not specified
CNA Linux Linux affected 22e9947a4b2ba255888541bd0111cf00b9b16586 330249609b70778094a7a36f5b6bcfa6362121d4 git Not specified
CNA Linux Linux affected 22e9947a4b2ba255888541bd0111cf00b9b16586 deff41898a5ae3a47db5fa1896a494aa95efda5d git Not specified
CNA Linux Linux affected 22e9947a4b2ba255888541bd0111cf00b9b16586 95376fe9c145be35566991df99c53134943d992f git Not specified
CNA Linux Linux affected 22e9947a4b2ba255888541bd0111cf00b9b16586 466f187b501a5ac8e1ea2ccf3ccd5c46108d8830 git Not specified
CNA Linux Linux affected 22e9947a4b2ba255888541bd0111cf00b9b16586 b5fa40226e71c17847b9ff2816c6ca4133d0d994 git Not specified
CNA Linux Linux affected 6.1 Not specified
CNA Linux Linux unaffected 6.1 semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.148 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.101 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.42 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.6 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/965b5bc8cf5031225e057979ce660fec2bd5fbfc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/330249609b70778094a7a36f5b6bcfa6362121d4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b5fa40226e71c17847b9ff2816c6ca4133d0d994 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/466f187b501a5ac8e1ea2ccf3ccd5c46108d8830 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/95376fe9c145be35566991df99c53134943d992f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/deff41898a5ae3a47db5fa1896a494aa95efda5d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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