CVE-2019-18423
First published: Thu Oct 31 2019(Updated: )
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.
Credit: cve@mitre.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Xen Xen | >=4.8<=4.12.1 | |
| Debian Debian Linux | =9.0 | |
| Debian Debian Linux | =10.0 | |
| Fedoraproject Fedora | =29 | |
| Fedoraproject Fedora | =30 | |
| Fedoraproject Fedora | =31 | |
| debian/xen | 4.11.4+107-gef32c7afa2-1 4.14.6-1 4.14.5+94-ge49571868d-1 4.17.2+76-ge1f9cb16e2-1~deb12u1 4.17.2+76-ge1f9cb16e2-1 |
Never miss a vulnerability like this again
Sign up to SecAlerts for real-time vulnerability data matched to your software, aggregated from hundreds of sources.
Reference Links
- http://www.openwall.com/lists/oss-security/2019/10/31/4
- http://xenbits.xen.org/xsa/advisory-301.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2BQKX7M2RHCWDBKNPX4KEBI3MJIH6AYZ/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/I5WWPW4BSZDDW7VHU427XTVXV7ROOFFW/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/IZYATWNUGHRBG6I3TC24YHP5Y3J7I6KH/
- https://seclists.org/bugtraq/2020/Jan/21
- https://security.gentoo.org/glsa/202003-56
- https://www.debian.org/security/2020/dsa-4602
- https://xenbits.xen.org/xsa/advisory-301.html
- https://security-tracker.debian.org/tracker/CVE-2019-18423
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2BQKX7M2RHCWDBKNPX4KEBI3MJIH6AYZ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/I5WWPW4BSZDDW7VHU427XTVXV7ROOFFW/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IZYATWNUGHRBG6I3TC24YHP5Y3J7I6KH/
- collector/nvd-index
- collector/security-tracker-debian
- agent/weakness
- agent/references
- agent/author
- agent/severity
- agent/description
- agent/type
- agent/event
- agent/remedy
- agent/first-publish-date
- agent/last-modified-date
- agent/softwarecombine
- agent/tags
- collector/mitre-cve
- source/MITRE
- vendor/xen
- canonical/xen xen
- version/xen xen/4.8
- version/xen xen/4.12.1
- vendor/debian
- canonical/debian debian linux
- version/debian debian linux/9.0
- version/debian debian linux/10.0
- vendor/fedoraproject
- canonical/fedoraproject fedora
- version/fedoraproject fedora/29
- version/fedoraproject fedora/30
- version/fedoraproject fedora/31
- package-manager/debian