| Name | 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]] |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| linux (PTS) | jessie, jessie (lts) | 3.16.84-1 | vulnerable |
| stretch (security) | 4.9.320-2 | vulnerable | |
| stretch (lts), stretch | 4.9.320-3 | vulnerable | |
| buster (security), buster, buster (lts) | 4.19.316-1 | fixed | |
| bullseye | 5.10.223-1 | fixed | |
| bullseye (security) | 5.10.226-1 | fixed | |
| bookworm | 6.1.115-1 | fixed | |
| bookworm (security) | 6.1.112-1 | fixed | |
| trixie | 6.11.7-1 | fixed | |
| sid | 6.11.9-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| linux | source | jessie | (unfixed) | end-of-life | ||
| linux | source | stretch | (unfixed) | end-of-life | ||
| linux | source | buster | (not affected) | |||
| linux | source | bullseye | 5.10.84-1 | |||
| linux | source | (unstable) | 5.15.3-1 |
[buster] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/a4aeaa06d45e90f9b279f0b09de84bd00006e733 (5.15)