CVE-2018-1000200

Published: 23 April 2018

The Linux Kernel versions 4.14, 4.15, and 4.16 has a null pointer dereference which can result in an out of memory (OOM) killing of large mlocked processes. The issue arises from an oom killed process's final thread calling exit_mmap(), which calls munlock_vma_pages_all() for mlocked vmas.This can happen synchronously with the oom reaper's unmap_page_range() since the vma's VM_LOCKED bit is cleared before munlocking (to determine if any other vmas share the memory and are mlocked).

From the Ubuntu Security Team

It was discovered that, when attempting to handle an out-of-memory situation, a null pointer dereference could be triggered in the Linux kernel in some circumstances. A local attacker could use this to cause a denial of service (system crash).

Notes

Proposed fix (v2): https://marc.info/?l=linux-kernel&m=152401997210084&w=2
Proposed fix (v3): https://marc.info/?l=linux-kernel&m=152460926619256

Status

Severity score breakdown

References

• http://openwall.com/lists/oss-security/2018/04/24/3
• https://ubuntu.com/security/notices/USN-3752-1
• https://ubuntu.com/security/notices/USN-3752-2
• https://ubuntu.com/security/notices/USN-3752-3
• https://www.cve.org/CVERecord?id=CVE-2018-1000200
• NVD
• Launchpad
• Debian