ISSUE DESCRIPTION =================

Guests are currently permitted to modify all of the (writable) bits in the PCI command register of devices passed through to them. This in particular allows them to disable memory and I/O decoding on the device unless the device is an SR-IOV virtual function, in which case subsequent accesses to the respective MMIO or I/O port ranges would - - on PCI Express devices - lead to Unsupported Request responses. The treatmeant of such errors is platform specific.

IMPACT ======

In the event that the platform surfaces aforementioned UR responses as Non-Maskable Interrupts, and either the OS is configured to treat NMIs as fatal or (e.g. via ACPI's APEI) the platform tells the OS to treat these errors as fatal, the host would crash, leading to a Denial of Service.

VULNERABLE SYSTEMS ==================

Xen versions 3.3 and onwards are vulnerable due to supporting PCI pass-through. Upstream Linux versions 3.1 and onwards are vulnerable due to supporting PCI backend functionality. Other Linux versions as well as other OS versions may be vulnerable too.

Any domain which is given access to a non-SR-IOV virtual function PCI Express device can take advantage of this vulnerability.

MITIGATION ==========

This issue can be avoided by not assigning PCI Express devices other than SR-IOV virtual functions to untrusted guests.

RESOLUTION ==========

Applying the attached patch resolves this issue for upstream Linux.

xsa120.patch Linux 3.19

$ sha256sum xsa120.patch 5167215293d4a8a05f090fca5b20eb5878213a0158a0e7a12c245553db81a855 xsa120.patch

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USN-4127-1 fixed several vulnerabilities in Python. This update provides the corresponding update for Ubuntu 12.04 ESM and Ubuntu 14.04 ESM. Original advisory details: It was discovered that Python incorrectly handled certain pickle files. An attacker could possibly use this issue to consume memory, leading to a denial of service. This issue only affected Ubuntu 14.04 ESM. (CVE-2018-20406) It was discovered that Python incorrectly validated the domain when handling cookies. An attacker could possibly trick Python into sending cookies to the wrong domain. (CVE-2018-20852) Jonathan Birch and Panayiotis Panayiotou discovered that Python incorrectly handled Unicode encoding during NFKC normalization. An attacker could possibly use this issue to obtain sensitive information. (CVE-2019-9636, CVE-2019-10160) Colin Read and Nicolas Edet discovered that Python incorrectly handled parsing certain X509 certificates. An attacker could possibly use this issue to cause Python to crash, resulting in a denial of service. This issue only affected Ubuntu 14.04 ESM. (CVE-2019-5010) It was discovered that Python incorrectly handled certain urls. A remote attacker could possibly use this issue to perform CRLF injection attacks. (CVE-2019-9740, CVE-2019-9947) Sihoon Lee discovered that Python incorrectly handled the localfile: scheme. A remote attacker could possibly use this issue to bypass blocklist meschanisms. (CVE-2019-9948)