Bug 1568744 (CVE-2018-1000200)

Summary: CVE-2018-1000200 kernel: NULL pointer dereference on OOM kill of large mlocked process
Product: [Other] Security Response Reporter: Adam Mariš <amaris>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: airlied, aquini, bhu, blc, bskeggs, dhoward, ewk, fhrbata, hdegoede, hkrzesin, hwkernel-mgr, iboverma, ichavero, itamar, jarodwilson, jforbes, jglisse, jkacur, john.j5live, jonathan, josef, jross, jwboyer, kernel-maint, kernel-mgr, labbott, lgoncalv, linville, matt, mchehab, mcressma, mjg59, mlangsdo, nmurray, plougher, rt-maint, rvrbovsk, security-response-team, skozina, steved, vdronov, williams, wmealing
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the Linux kernel where an out of memory (oom) killing of a process that has large spans of mlocked memory can result in deferencing a NULL pointer, leading to denial of service.
Story Points: ---
Clone Of: Environment:
Last Closed: 2019-06-10 10:20:05 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 1570542, 1571595, 1571596    
Bug Blocks: 1568749    

Description Adam Mariš 2018-04-18 08:29:27 UTC
It was found that out of memory (oom) killing a process that has large spans of mlocked memory can result in deferencing a NULL pointer, leading to denial of service.

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).





Introduced by:


An upstream patch:


Comment 1 Adam Mariš 2018-04-18 08:29:30 UTC

Name: David Rientjes (Google)

Comment 6 Adam Mariš 2018-04-25 07:58:22 UTC
Public via:


Comment 7 Adam Mariš 2018-04-25 07:59:21 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1571596]

Comment 9 Justin M. Forbes 2018-04-25 12:17:05 UTC
This was fixed for Fedora with the 4.15 rebases

Comment 12 errata-xmlrpc 2018-10-30 09:00:04 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2018:2948 https://access.redhat.com/errata/RHSA-2018:2948