mm: do file ownership checks with the proper mount idmap
Summary
| CVE | CVE-2026-64294 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-25 10:17:10 UTC |
| Updated | 2026-07-30 15:00:27 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: mm: do file ownership checks with the proper mount idmap Ever since idmapped mounts were introduced, inode ownership checks (for side-channel protection) in mincore() and madvise(MADV_PAGEOUT) were done against the nop_mnt_idmap, which completely ignores the file's mount's idmap. This results in odd edgecases like: 1) mount/bind-mount with an idmap userA:userB:1 2) userB runs an owner_or_capable() check on file that is owned by userA on-disk/in-memory, but owned by userB after idmap translation 3) owner_or_capable() mysteriously fails as the correct idmap wasn't supplied In the case of mincore/madvise MADV_PAGEOUT, this is usually benign, because file_permission(file, MAY_WRITE) will probably succeed, as it uses the proper idmap internally, but it does not need to be the case on e.g a 0444 file where even the owner itself doesn't have permissions to write to it. Since this is clearly not trivial to get right, introduce a file_owner_or_capable() that can carry the correct semantics, and switch the various users in mm to it. The issue was found by manual code inspection & an off-list discussion with Jan Kara. |
Risk And Classification
EPSS: 0.002000000 probability, percentile 0.100790000 (date 2026-08-02)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 9caccd41541a6f7d6279928d9f971f6642c361af 744b23aa430d52f5c8e4dbff7d71496d6643bed2 git | Not specified |
| CNA | Linux | Linux | affected 9caccd41541a6f7d6279928d9f971f6642c361af 8344bdf0629457e532797b42d9d2bbf2a2900bbf git | Not specified |
| CNA | Linux | Linux | affected 9caccd41541a6f7d6279928d9f971f6642c361af 5c942ad7df75925ee166e7f0fb36892d8dde376b git | Not specified |
| CNA | Linux | Linux | affected 9caccd41541a6f7d6279928d9f971f6642c361af 04ba248d02d9eaa3d9077b00a6134caa75fa3e90 git | Not specified |
| CNA | Linux | Linux | affected 9caccd41541a6f7d6279928d9f971f6642c361af e187bc02f8fa4226d62814592cf064ee4557c470 git | Not specified |
| CNA | Linux | Linux | affected 5.12 | Not specified |
| CNA | Linux | Linux | unaffected 5.12 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.145 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.96 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.39 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1.4 7.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2-rc3 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/5c942ad7df75925ee166e7f0fb36892d8dde376b | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/8344bdf0629457e532797b42d9d2bbf2a2900bbf | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/04ba248d02d9eaa3d9077b00a6134caa75fa3e90 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/e187bc02f8fa4226d62814592cf064ee4557c470 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/744b23aa430d52f5c8e4dbff7d71496d6643bed2 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.