Bug 1680540 (CVE-2018-20784)

Summary: CVE-2018-20784 kernel: infinite loop in update_blocked_averages() in kernel/sched/fair.c leading to denial of service
Product: [Other] Security Response Reporter: msiddiqu
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: jforbes, vdronov, yozone
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
The CFS Linux kernel scheduler mishandles handling of leaf cfs_rq's in the kernel/sched/fair.c code, which allows a local unprivileged attacker to cause a denial of service (DoS) by entering an infinite loop in update_blocked_averages() function by inducing a high load on a system. Due to the nature of the flaw, a remote network attack (by initiating a magnitude of remote requests) cannot be fully ruled out.
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Clone Of: Environment:
Last Closed: 2019-07-30 13:18:23 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1680544, 1685635, 1685636, 1685637, 1715343, 1716872    
Bug Blocks: 1680575    

Description msiddiqu 2019-02-25 10:01:42 UTC 
The CFS Linux kernel scheduler mishandles handling of leaf cfs_rq's in the kernel/sched/fair.c code, which allows a local unprivileged attacker to cause a denial of service (DoS) by entiring the infinite loop in update_blocked_averages() function by inducing a high load on a system. Due to the nature of the flaw, a remote network attack (by initiating a magnitude of remote requests) cannot be fully ruled out, although we believe it is unlikely.

References:

https://lore.kernel.org/lkml/1545879866-27809-1-git-send-email-xiexiuqi@huawei.com/T/#u

An upstream patch:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c40f7d74c741a907cfaeb73a7697081881c497d0
Comment 1 msiddiqu 2019-02-25 10:03:34 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1680544]
Comment 3 Justin M. Forbes 2019-02-25 13:04:08 UTC 
This was fixed for Fedora with the 4.20 stable rebases.
Comment 7 errata-xmlrpc 2019-07-30 09:42:15 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2019:1959 https://access.redhat.com/errata/RHSA-2019:1959
Comment 8 errata-xmlrpc 2019-07-30 11:02:05 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2019:1971 https://access.redhat.com/errata/RHSA-2019:1971
Comment 9 Product Security DevOps Team 2019-07-30 13:18:23 UTC 
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2018-20784