Bug 2048926

Summary:	CVE-2021-45956 dnsmasq: a heap-based buffer overflow in print_mac [fedora-all]
Product:	[Fedora] Fedora	Reporter:	Marian Rehak <mrehak>
Component:	dnsmasq	Assignee:	Petr Menšík <pemensik>
Status:	CLOSED NOTABUG	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	high
Version:	35	CC:	aegorenk, code, dns-sig, dougsland, pemensik, veillard
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	No Doc Update
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2022-02-16 23:39:17 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:
Bug Blocks:	2048925

Description Marian Rehak 2022-02-01 08:18:14 UTC

This is an automatically created tracking bug!  It was created to ensure
that one or more security vulnerabilities are fixed in affected versions
of fedora-all.

For comments that are specific to the vulnerability please use bugs filed
against the "Security Response" product referenced in the "Blocks" field.

For more information see:
http://fedoraproject.org/wiki/Security/TrackingBugs

When submitting as an update, use the fedpkg template provided in the next
comment(s).  This will include the bug IDs of this tracking bug as well as
the relevant top-level CVE bugs.

Please also mention the CVE IDs being fixed in the RPM changelog and the
fedpkg commit message.

NOTE: this issue affects multiple supported versions of Fedora. While only
one tracking bug has been filed, please correct all affected versions at
the same time.  If you need to fix the versions independent of each other,
you may clone this bug as appropriate.

Comment 1 Marian Rehak 2022-02-01 08:18:16 UTC

Use the following template to for the 'fedpkg update' request to submit an
update for this issue as it contains the top-level parent bug(s) as well as
this tracking bug.  This will ensure that all associated bugs get updated
when new packages are pushed to stable.

=====

# bugfix, security, enhancement, newpackage (required)
type=security

# low, medium, high, urgent (required)
severity=high

# testing, stable
request=testing

# Bug numbers: 1234,9876
bugs=2048925,2048926

# Description of your update
notes=Security fix for [PUT CVEs HERE]

# Enable request automation based on the stable/unstable karma thresholds
autokarma=True
stable_karma=3
unstable_karma=-3

# Automatically close bugs when this marked as stable
close_bugs=True

# Suggest that users restart after update
suggest_reboot=False

======

Additionally, you may opt to use the bodhi web interface to submit updates:

https://bodhi.fedoraproject.org/updates/new

Comment 2 Petr Menšík 2022-02-16 23:39:17 UTC

Were not yet able to reproduce in own build to revalidate.

I think this is invalid CVE, because detected problem is created in fuzzer instead of dnsmasq. Should be fixed by my proposal in oss-fuzz project instead [1].

This is just indirectly related, because print_mac() function uses daemon->namebuff also. If that buffer is not large enough, it would detect writing behind allocated memory. But that happens because on 76 bytes were allocated to daemon->namebuff, which should have got at least MAXDNAME size.

1. https://github.com/google/oss-fuzz/pull/7293