{"id":"CVE-2021-47491","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: khugepaged: skip huge page collapse for special files\n\nThe read-only THP for filesystems will collapse THP for files opened\nreadonly and mapped with VM_EXEC.  The intended usecase is to avoid TLB\nmisses for large text segments.  But it doesn't restrict the file types\nso a THP could be collapsed for a non-regular file, for example, block\ndevice, if it is opened readonly and mapped with EXEC permission.  This\nmay cause bugs, like [1] and [2].\n\nThis is definitely not the intended usecase, so just collapse THP for\nregular files in order to close the attack surface.\n\n[shy828301@gmail.com: fix vm_file check [3]]","modified":"2026-03-15T14:45:50.548424Z","published":"2024-05-22T09:15:10.917Z","related":["SUSE-SU-2024:2008-1","SUSE-SU-2024:2011-1","SUSE-SU-2024:2019-1","SUSE-SU-2024:2189-1","SUSE-SU-2024:2190-1","SUSE-SU-2025:0231-1"],"references":[{"type":"FIX","url":"https://git.kernel.org/stable/c/5fcb6fce74ffa614d964667110cf1a516c48c6d9"},{"type":"FIX","url":"https://git.kernel.org/stable/c/6d67b2a73b8e3a079c355bab3c1aef7d85a044b8"},{"type":"FIX","url":"https://git.kernel.org/stable/c/a4aeaa06d45e90f9b279f0b09de84bd00006e733"}],"affected":[{"database_specific":{"unresolved_ranges":[{"events":[{"introduced":"5.4"},{"fixed":"5.10.78"}]},{"events":[{"introduced":"5.11"},{"fixed":"5.14.16"}]},{"events":[{"introduced":"0"},{"last_affected":"5.15-rc1"}]},{"events":[{"introduced":"0"},{"last_affected":"5.15-rc2"}]},{"events":[{"introduced":"0"},{"last_affected":"5.15-rc3"}]},{"events":[{"introduced":"0"},{"last_affected":"5.15-rc4"}]},{"events":[{"introduced":"0"},{"last_affected":"5.15-rc5"}]},{"events":[{"introduced":"0"},{"last_affected":"5.15-rc6"}]},{"events":[{"introduced":"0"},{"last_affected":"5.15-rc7"}]}],"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-47491.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}