CVE-2019-18423

Summary

CVE	CVE-2019-18423
State	PUBLIC
Assigner	[email protected]
Source Priority	CVE Program / NVD first with legacy fallback
Published	2019-10-31 14:15:00 UTC
Updated	2023-11-07 03:06:00 UTC
Description	An issue was discovered in Xen through 4.12.x allowing ARM guest OS users to cause a denial of service via a XENMEM_add_to_physmap hypercall. p2m->max_mapped_gfn is used by the functions p2m_resolve_translation_fault() and p2m_get_entry() to sanity check guest physical frame. The rest of the code in the two functions will assume that there is a valid root table and check that with BUG_ON(). The function p2m_get_root_pointer() will ignore the unused top bits of a guest physical frame. This means that the function p2m_set_entry() will alias the frame. However, p2m->max_mapped_gfn will be updated using the original frame. It would be possible to set p2m->max_mapped_gfn high enough to cover a frame that would lead p2m_get_root_pointer() to return NULL in p2m_get_entry() and p2m_resolve_translation_fault(). Additionally, the sanity check on p2m->max_mapped_gfn is off-by-one allowing "highest mapped + 1" to be considered valid. However, p2m_get_root_pointer() will return NULL. The problem could be triggered with a specially crafted hypercall XENMEM_add_to_physmap{, _batch} followed by an access to an address (via hypercall or direct access) that passes the sanity check but cause p2m_get_root_pointer() to return NULL. A malicious guest administrator may cause a hypervisor crash, resulting in a Denial of Service (DoS). Xen version 4.8 and newer are vulnerable. Only Arm systems are vulnerable. x86 systems are not affected.

Risk And Classification

Problem Types: CWE-193

NVD Known Affected Configurations (CPE 2.3)

Type	Vendor	Product	Version	Update	Edition	Language
Operating System	Debian	Debian Linux	10.0	All	All	All
Operating System	Debian	Debian Linux	9.0	All	All	All
Operating System	Fedoraproject	Fedora	29	All	All	All
Operating System	Fedoraproject	Fedora	30	All	All	All
Operating System	Fedoraproject	Fedora	31	All	All	All
Operating System	Xen	Xen	All	All	All	All

References

Reference	Source	Link	Tags
Debian -- Security Information -- DSA-4602-1 xen	DEBIAN	www.debian.org
Xen: Multiple vulnerabilities (GLSA 202003-56) — Gentoo security	GENTOO	security.gentoo.org
[SECURITY] Fedora 30 Update: xen-4.11.2-3.fc30 - package-announce - Fedora Mailing-Lists		lists.fedoraproject.org
[SECURITY] Fedora 29 Update: xen-4.11.2-2.fc29 - package-announce - Fedora Mailing-Lists		lists.fedoraproject.org
[SECURITY] Fedora 29 Update: xen-4.11.2-2.fc29 - package-announce - Fedora Mailing-Lists	FEDORA	lists.fedoraproject.org
Bugtraq: [SECURITY] [DSA 4602-1] xen security update	BUGTRAQ	seclists.org
oss-security - Xen Security Advisory 301 v3 (CVE-2019-18423) - add-to-physmap can be abused to DoS Arm hosts	MLIST	www.openwall.com	Mailing List, Patch, Third Party Advisory
[SECURITY] Fedora 31 Update: xen-4.12.1-6.fc31 - package-announce - Fedora Mailing-Lists	FEDORA	lists.fedoraproject.org
XSA-301 - Xen Security Advisories	MISC	xenbits.xen.org	Patch, Vendor Advisory
[SECURITY] Fedora 31 Update: xen-4.12.1-6.fc31 - package-announce - Fedora Mailing-Lists		lists.fedoraproject.org
[SECURITY] Fedora 30 Update: xen-4.11.2-3.fc30 - package-announce - Fedora Mailing-Lists	FEDORA	lists.fedoraproject.org
CVE Program record	CVE.ORG	www.cve.org	canonical
NVD vulnerability detail	NVD	nvd.nist.gov	canonical, analysis

No vendor comments have been submitted for this CVE.

Legacy QID Mappings

500754 Alpine Linux Security Update for xen
504531 Alpine Linux Security Update for xen