Bug 1455493 (CVE-2017-9217)

Summary:	CVE-2017-9217 systemd: Null pointer dereference in dns_packet_is_reply_for function
Product:	[Other] Security Response	Reporter:	Adam Mariš <amaris>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	johannbg, lnykryn, msekleta, muadda, s, systemd-maint-list, systemd-maint, zbyszek
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-06-08 03:13:27 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:	1455495
Bug Blocks:	1457410

Description Adam Mariš 2017-05-25 10:38:15 UTC

systemd-resolved through 233 allows remote attackers to cause a denial of service (daemon crash) via a crafted DNS response with an empty question section.

Upstream bug:

https://github.com/systemd/systemd/pull/5998

Upstream patch:

https://github.com/systemd/systemd/pull/6020/commits/9e74e781f176f3b930d9c202e20532f011a5d7bc

Comment 1 Adam Mariš 2017-05-25 10:38:49 UTC

Created systemd tracking bugs for this issue:

Affects: fedora-all [bug 1455495]

Comment 4 Adam Mariš 2017-06-02 09:01:53 UTC

Analysis:

The issue was introduced in systemd v225 by following commit:

https://github.com/systemd/systemd/commit/f52e61da047d7fc74e83f12dbbf87e0cbcc51c73

The vulnerable code (dereferencing p->question->n_keys without first asserting on p->question) was first introduced in dns_transaction_process_reply function and later transferred to dns_packet_is_reply_for while doing refactoring in the following commit:

https://github.com/systemd/systemd/commit/8af5b883227ac8dfa796742b9edcc1647a5d4d6c

RHEL-7 ships systemd v219 that does not have this vulnerability.

Comment 5 Adam Mariš 2017-06-02 09:03:45 UTC

Statement:

This issue did not affect the versions of systemd as shipped with Red Hat Enterprise Linux 7.