CVE-2021-47491
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.
Does this matter?
Lower severity and a low EPSS score (0.21%). Track it; it rarely justifies an emergency change on its own.
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]]
- CVSS 3.1
- 5.5 MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.21% probability · 11th percentile
- CISA KEV
- Not listed
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/5fcb6fce74ffa614d964667110cf1a516c48c6d9Patch
- https://git.kernel.org/stable/c/6d67b2a73b8e3a079c355bab3c1aef7d85a044b8Patch
- https://git.kernel.org/stable/c/a4aeaa06d45e90f9b279f0b09de84bd00006e733Patch
- https://git.kernel.org/stable/c/5fcb6fce74ffa614d964667110cf1a516c48c6d9Patch
- https://git.kernel.org/stable/c/6d67b2a73b8e3a079c355bab3c1aef7d85a044b8Patch
- https://git.kernel.org/stable/c/a4aeaa06d45e90f9b279f0b09de84bd00006e733Patch
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.