CVE-2021-47491
- Source
- https://nvd.nist.gov/vuln/detail/CVE-2021-47491
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-47491.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2021-47491
- Downstream
- Related
- Published
- 2024-05-22T09:15:10Z
- Modified
- 2025-09-29T16:37:28Z
- Severity
-
- 5.5 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
- Summary
- [none]
- Details
-
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]]
- References