Bug 1623009 (CVE-2018-15853) - CVE-2018-15853 libxkbcommon: Endless recursion in xkbcomp/expr.c resulting in a crash
Summary: CVE-2018-15853 libxkbcommon: Endless recursion in xkbcomp/expr.c resulting in...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2018-15853
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1623038 1642852 1642853
Blocks: 1623044
TreeView+ depends on / blocked
 
Reported: 2018-08-28 11:47 UTC by Andrej Nemec
Modified: 2019-09-29 14:57 UTC (History)
3 users (show)

Fixed In Version: libxkbcommon 0.8.1
Doc Type: If docs needed, set a value
Doc Text:
An uncontrolled recursion flaw was found in libxkbcommon in the way it parses boolean expressions. A specially crafted file provided to xkbcomp could crash the application.
Clone Of:
Environment:
Last Closed: 2019-08-06 19:19:23 UTC
Embargoed:

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System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2019:2079 0 None None None 2019-08-06 12:11:10 UTC

Description Andrej Nemec 2018-08-28 11:47:07 UTC 
Endless recursion exists in xkbcomp/expr.c in xkbcommon and libxkbcommon before 0.8.1, which could be used by local attackers to crash xkbcommon users by supplying a crafted keymap file that triggers boolean negation.

Upstream patch:

https://github.com/xkbcommon/libxkbcommon/commit/1f9d1248c07cda8aaff762429c0dce146de8632a

References:

https://lists.freedesktop.org/archives/wayland-devel/2018-August/039232.html
Comment 2 Riccardo Schirone 2018-10-25 08:34:34 UTC 
Created libxkbcommon tracking bugs for this issue:

Affects: fedora-all [bug 1642852]
Comment 3 Riccardo Schirone 2018-10-25 08:36:04 UTC 
When parsing a boolean expression that is composed by another boolean expression, like a negated expression, the ExprResolveBoolean() function is recursively called, but on the same expression that was currently analyzed and not on the sub-expression, causing an infinite recursion.
Comment 6 errata-xmlrpc 2019-08-06 12:11:10 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2019:2079 https://access.redhat.com/errata/RHSA-2019:2079
Comment 7 Product Security DevOps Team 2019-08-06 19:19:23 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-2018-15853
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