ID CVE-2019-18423
Summary 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.
References
Vulnerable Configurations
  • cpe:2.3:o:xen:xen:4.8.0:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.8.0:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.8.1:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.8.1:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.8.2:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.8.2:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.8.3:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.8.3:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.8.4:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.8.4:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.8.5:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.8.5:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.9.0:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.9.0:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.9.1:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.9.1:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.9.2:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.9.2:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.9.3:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.9.3:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.9.4:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.9.4:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.10.0:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.10.0:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.10.1:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.10.1:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.10.2:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.10.2:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.10.3:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.10.3:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.10.4:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.10.4:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.11.0:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.11.0:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.11.1:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.11.1:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.11.2:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.11.2:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.11.3:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.11.3:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.12.0:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.12.0:*:*:*:*:*:arm:*
  • cpe:2.3:o:xen:xen:4.12.1:*:*:*:*:*:arm:*
    cpe:2.3:o:xen:xen:4.12.1:*:*:*:*:*:arm:*
CVSS
Base: 8.5 (as of 24-08-2020 - 17:37)
Impact:
Exploitability:
CWE CWE-193
CAPEC
Access
VectorComplexityAuthentication
NETWORK MEDIUM SINGLE
Impact
ConfidentialityIntegrityAvailability
COMPLETE COMPLETE COMPLETE
cvss-vector via4 AV:N/AC:M/Au:S/C:C/I:C/A:C
refmap via4
bugtraq 20200114 [SECURITY] [DSA 4602-1] xen security update
debian DSA-4602
fedora
  • FEDORA-2019-376ec5c107
  • FEDORA-2019-865bb16900
  • FEDORA-2019-cbb732f760
gentoo GLSA-202003-56
misc http://xenbits.xen.org/xsa/advisory-301.html
mlist [oss-security] 20191031 Xen Security Advisory 301 v3 (CVE-2019-18423) - add-to-physmap can be abused to DoS Arm hosts
Last major update 24-08-2020 - 17:37
Published 31-10-2019 - 14:15
Last modified 24-08-2020 - 17:37
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