CVE-2018-18281 Information

Description

Since Linux kernel version 3.2 the mremap() syscall performs TLB flushes after dropping pagetable locks. If a syscall such as ftruncate() removes entries from the pagetables of a task that is in the middle of mremap() a stale TLB entry can remain for a short time that permits access to a physical page after it has been released back to the page allocator and reused. This is fixed in the following kernel versions: 4.9.135 4.14.78 4.18.16 4.19.

CVSS Vector

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Reference

http://packetstormsecurity.com/files/150001/Linux-mremap-TLB-Flush-Too-Late.html http://www.openwall.com/lists/oss-security/2018/10/29/5 http://www.securityfocus.com/bid/105761 http://www.securityfocus.com/bid/106503 https://access.redhat.com/errata/RHSA-2019:0831 https://access.redhat.com/errata/RHSA-2019:2029 https://access.redhat.com/errata/RHSA-2019:2043 https://access.redhat.com/errata/RHSA-2020:0036 https://access.redhat.com/errata/RHSA-2020:0100 https://access.redhat.com/errata/RHSA-2020:0103 https://access.redhat.com/errata/RHSA-2020:0179 https://bugs.chromium.org/p/project-zero/issues/detail?id=1695 https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.14.78 https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.18.16 https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.9.135 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=eb66ae030829605d61fbef1909ce310e29f78821 https://lists.debian.org/debian-lts-announce/2019/03/msg00017.html https://lists.debian.org/debian-lts-announce/2019/03/msg00034.html https://lists.debian.org/debian-lts-announce/2019/04/msg00004.html https://usn.ubuntu.com/3832-1/ https://usn.ubuntu.com/3835-1/ https://usn.ubuntu.com/3871-1/ https://usn.ubuntu.com/3871-3/ https://usn.ubuntu.com/3871-4/ https://usn.ubuntu.com/3871-5/ https://usn.ubuntu.com/3880-1/ https://usn.ubuntu.com/3880-2/

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

7.8