CVE-2021-47491
Description
In the Linux kernel, the following vulnerability has been resolved: mm: khugepaged: skip huge page collapse for special files The read-only THP for filesystems will collapse THP for files opened readonly and mapped with VM_EXEC. The intended usecase is to avoid TLB misses for large text segments. But it doesn't restrict the file types so a THP could be collapsed for a non-regular file, for example, block device, if it is opened readonly and mapped with EXEC permission. This may cause bugs, like [1] and [2]. This is definitely not the intended usecase, so just collapse THP for regular files in order to close the attack surface. [shy828301@gmail.com: fix vm_file check [3]]
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
AlmaLinux Fixed 1 release
| Version | Status | Fixed in |
|---|---|---|
| 8 | Fixed | kernel-rt-debug-4.18.0-553.16.1.rt7.357.el8_10.x86_64.rpm |
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 5.15.3-1 |
| sid | Fixed | 5.15.3-1 |
| forky | Fixed | 5.15.3-1 |
| bullseye | Fixed | 5.10.84-1 |
| bookworm | Fixed | 5.15.3-1 |
Red Hat Fixed 1 release
| Version | Status | Fixed in |
|---|---|---|
| 8 | Fixed | — |
Rocky Linux Fixed 1 release
| Version | Status | Fixed in |
|---|---|---|
| 8 | Fixed | — |
References
- https://errata.rockylinux.org/RXSA-2024:5101
- https://errata.rockylinux.org/RLSA-2024:5102
- https://errata.rockylinux.org/RLSA-2024:5101
- https://www.suse.com/security/cve/CVE-2021-47491.html
- https://security-tracker.debian.org/tracker/CVE-2021-47491
- https://access.redhat.com/errata/RHSA-2024:5102
- https://bugzilla.redhat.com/2263879
- https://bugzilla.redhat.com/2265645
- https://bugzilla.redhat.com/2265797
- https://bugzilla.redhat.com/2266341
- https://bugzilla.redhat.com/2266347
- https://bugzilla.redhat.com/2266497
- https://bugzilla.redhat.com/2267787
- https://bugzilla.redhat.com/2268118
- https://bugzilla.redhat.com/2269070
- https://bugzilla.redhat.com/2269211
- https://bugzilla.redhat.com/2270084
- https://bugzilla.redhat.com/2270100
- https://bugzilla.redhat.com/2271686
- https://bugzilla.redhat.com/2271688
- https://bugzilla.redhat.com/2272782
- https://bugzilla.redhat.com/2272795
- https://bugzilla.redhat.com/2273109
- https://bugzilla.redhat.com/2273174
- https://bugzilla.redhat.com/2273236
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.