An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service because of a bad error path in GNTTABOP_map_grant. Grant table operations are expected to return 0 for success, and a negative number for errors. Some misplaced brackets cause one error path to return 1 instead of a negative value. The grant table code in Linux treats this condition as success, and proceeds with incorrectly initialised state. A buggy or malicious guest can construct its grant table in such a way that, when a backend domain tries to map a grant, it hits the incorrect error path. This will crash a Linux based dom0 or backend domain.

The remote Ubuntu 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-5617-1 advisory.

    It was discovered that memory contents previously stored in microarchitectural special registers after     RDRAND, RDSEED, and SGX EGETKEY read operations on Intel client and Xeon E3 processors may be briefly     exposed to processes on the same or different processor cores. A local attacker could use this to expose     sensitive information. (CVE-2020-0543)

    Julien Grall discovered that Xen incorrectly handled memory barriers on ARM-based systems. An attacker     could possibly use this issue to cause a denial of service, obtain sensitive information or escalate     privileges. (CVE-2020-11739)

    Ilja Van Sprundel discovered that Xen incorrectly handled profiling of guests. An unprivileged attacker     could use this issue to obtain sensitive information from other guests, cause a denial of service or     possibly gain privileges. (CVE-2020-11740, CVE-2020-11741)

    It was discovered that Xen incorrectly handled grant tables. A malicious guest could possibly use this     issue to cause a denial of service. (CVE-2020-11742, CVE-2020-11743)

    Jan Beulich discovered that Xen incorrectly handled certain code paths. An attacker could possibly use     this issue to cause a denial of service. (CVE-2020-15563)

    Julien Grall discovered that Xen incorrectly verified memory addresses provided by the guest on ARM-based     systems. A malicious guest administrator could possibly use this issue to cause a denial of service.
    (CVE-2020-15564)

    Roger Pau Monn discovered that Xen incorrectly handled caching on x86 Intel systems. An attacker could     possibly use this issue to cause a denial of service. (CVE-2020-15565)

    It was discovered that Xen incorrectly handled error in event-channel port allocation. A malicious guest     could possibly use this issue to cause a denial of service. (CVE-2020-15566)

    Jan Beulich discovered that Xen incorrectly handled certain EPT (Extended Page Tables).

    An attacker could possibly use this issue to cause a denial of service, data corruption or privilege     escalation. (CVE-2020-15567)

    Andrew Cooper discovered that Xen incorrectly handled PCI passthrough. An attacker could possibly use this     issue to cause a denial of service. (CVE-2020-25595)

    Andrew Cooper discovered that Xen incorrectly sanitized path injections. An attacker could possibly use     this issue to cause a denial of service. (CVE-2020-25596)

    Jan Beulich discovered that Xen incorrectly handled validation of event channels. An attacker could     possibly use this issue to cause a denial of service. (CVE-2020-25597)

    Julien Grall and Jan Beulich discovered that Xen incorrectly handled resetting event channels. An attacker     could possibly use this issue to cause a denial of service or obtain sensitive information.
    (CVE-2020-25599)

    Julien Grall discovered that Xen incorrectly handled event channels memory allocation on 32-bits domains.
    An attacker could possibly use this issue to cause a denial of service. (CVE-2020-25600)

    Jan Beulich discovered that Xen incorrectly handled resetting or cleaning up event channels. An attacker     could possibly use this issue to cause a denial of service. (CVE-2020-25601)

    Andrew Cooper discovered that Xen incorrectly handled certain Intel specific MSR (Model Specific     Registers). An attacker could possibly use this issue to cause a denial of service. (CVE-2020-25602)

    Julien Grall discovered that Xen incorrectly handled accessing/allocating event channels. An attacker     could possibly use this issue to cause a denial of service, obtain sensitive information of privilege     escalation. (CVE-2020-25603)

    Igor Druzhinin discovered that Xen incorrectly handled locks. An attacker could possibly use this issue to     cause a denial of service. (CVE-2020-25604)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Multiple vulnerabilities have been discovered in the Xen hypervisor, which could result in denial of service, guest-to-host privilege escalation or information leaks.

The remote host is affected by the vulnerability described in GLSA-202005-08 (Xen: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in Xen. Please review the       CVE identifiers referenced below for details.
  Impact :

    Please review the referenced CVE identifiers for details.
  Workaround :

    There is no known workaround at this time.

update to 4.11.4

----

multiple xenoprof issues [XSA-313, CVE-2020-11740, CVE-2020-11741] (#1823912, #1823914) Missing memory barriers in read-write unlock paths [XSA-314, CVE-2020-11739] (#1823784) Bad error path in GNTTABOP_map_grant [XSA-316, CVE-2020-11743] (#1823926) Bad continuation handling in GNTTABOP_copy [XSA-318, CVE-2020-11742] (#1823943)

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update for xen fixes the following issues :

Security issues fixed :

  - CVE-2020-11742: Bad continuation handling in     GNTTABOP_copy (bsc#1169392).

  - CVE-2020-11740, CVE-2020-11741: xen: XSA-313 multiple     xenoprof issues (bsc#1168140).

  - CVE-2020-11739: Missing memory barriers in read-write     unlock paths (bsc#1168142).

  - CVE-2020-11743: Bad error path in GNTTABOP_map_grant     (bsc#1168143).

  - arm: a CPU may speculate past the ERET instruction     (bsc#1160932).

Non-security issues fixed :

  - Xenstored Crashed during VM install (bsc#1167152)

  - DomU hang: soft lockup CPU #0 stuck under high load     (bsc#1165206, bsc#1134506)

  - Update API compatibility versions, fixes issues for     libvirt. (bsc#1167007, bsc#1157490)

  - aacraid blocks xen commands (bsc#1155200)

This update was imported from the SUSE:SLE-15-SP1:Update update project.

multiple xenoprof issues [XSA-313, CVE-2020-11740, CVE-2020-11741] (#1823912, #1823914) Missing memory barriers in read-write unlock paths [XSA-314, CVE-2020-11739] (#1823784) Bad error path in GNTTABOP_map_grant [XSA-316, CVE-2020-11743] (#1823926) Bad continuation handling in GNTTABOP_copy [XSA-318, CVE-2020-11742] (#1823943)

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update for xen to version 4.12.2 fixes the following issues :

Security issues fixed :

CVE-2020-11742: Bad continuation handling in GNTTABOP_copy (bsc#1169392).

CVE-2020-11740, CVE-2020-11741: xen: XSA-313 multiple xenoprof issues (bsc#1168140).

CVE-2020-11739: Missing memory barriers in read-write unlock paths (bsc#1168142).

CVE-2020-11743: Bad error path in GNTTABOP_map_grant (bsc#1168143).

CVE-2020-7211: Fixed potential directory traversal using relative paths via tftp server on Windows host (bsc#1161181).

arm: a CPU may speculate past the ERET instruction (bsc#1160932).

Non-security issues fixed: Xenstored Crashed during VM install (bsc#1167152)

DomU hang: soft lockup CPU #0 stuck under high load (bsc#1165206, bsc#1134506)

Update API compatibility versions, fixes issues for libvirt.
(bsc#1167007, bsc#1157490)

aacraid blocks xen commands (bsc#1155200)

Problems Booting Fedora31 VM on sles15 sp1 Xen Dom0 (bsc#1162040).

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update for xen fixes the following issues :

Security issues fixed :

CVE-2020-11742: Bad continuation handling in GNTTABOP_copy (bsc#1169392).

CVE-2020-11740, CVE-2020-11741: xen: XSA-313 multiple xenoprof issues (bsc#1168140).

CVE-2020-11739: Missing memory barriers in read-write unlock paths (bsc#1168142).

CVE-2020-11743: Bad error path in GNTTABOP_map_grant (bsc#1168143).

CVE-2020-7211: Fixed potential directory traversal using relative paths via tftp server on Windows host (bsc#1161181).

arm: a CPU may speculate past the ERET instruction (bsc#1160932).

Non-security issues fixed: Xenstored Crashed during VM install (bsc#1167152)

DomU hang: soft lockup CPU #0 stuck under high load (bsc#1165206, bsc#1134506)

Update API compatibility versions, fixes issues for libvirt.
(bsc#1167007, bsc#1157490)

aacraid blocks xen commands (bsc#1155200)

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update for xen fixes the following issues :

Security issues fixed :

CVE-2020-11742: Bad continuation handling in GNTTABOP_copy (bsc#1169392).

CVE-2020-11740, CVE-2020-11741: xen: XSA-313 multiple xenoprof issues (bsc#1168140).

CVE-2020-11739: Missing memory barriers in read-write unlock paths (bsc#1168142).

CVE-2020-11743: Bad error path in GNTTABOP_map_grant (bsc#1168143).

arm: a CPU may speculate past the ERET instruction (bsc#1160932).

Non-security issues fixed :

Xenstored Crashed during VM install (bsc#1167152)

DomU hang: soft lockup CPU #0 stuck under high load (bsc#1165206, bsc#1134506)

Update API compatibility versions, fixes issues for libvirt.
(bsc#1167007, bsc#1157490)

aacraid blocks xen commands (bsc#1155200)

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

According to its self-reported version number, the Xen hypervisor installed on the remote host is affected by a denial of service vulnerability. Grant table operations are expected to return 0 for success, and a negative number for errors. Some misplaced brackets cause one error path to return 1 instead of a negative value. The grant table code in Linux treats this condition as success, and proceeds with incorrectly initialised state. A buggy or malicious guest can construct its grant table in such a way that, when a backend domain tries to map a grant, it hits the incorrect error path. This will crash a Linux based dom0 or backend domain. 

Note only systems with the XSA-295 patch applied are affected. All other hosts are not vulnerable.

ID	Name	Product	Family	Severity
165248	Ubuntu 20.04 LTS : Xen vulnerabilities (USN-5617-1)	Nessus	Ubuntu Local Security Checks	high
138394	Debian DSA-4723-1 : xen - security update	Nessus	Debian Local Security Checks	high
136638	GLSA-202005-08 : Xen: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	high
136438	Fedora 30 : xen (2020-cbc3149753)	Nessus	Fedora Local Security Checks	high
136312	openSUSE Security Update : xen (openSUSE-2020-599)	Nessus	SuSE Local Security Checks	high
136210	Fedora 31 : xen (2020-295ed0b1e0)	Nessus	Fedora Local Security Checks	high
136164	SUSE SLES12 Security Update : xen (SUSE-SU-2020:1139-1)	Nessus	SuSE Local Security Checks	high
136163	SUSE SLES12 Security Update : xen (SUSE-SU-2020:1138-1)	Nessus	SuSE Local Security Checks	high
136076	SUSE SLED15 / SLES15 Security Update : xen (SUSE-SU-2020:1124-1)	Nessus	SuSE Local Security Checks	high
135928	Xen Bad error path in GNTTABOP_map_grant DoS (XSA-316)	Nessus	Misc.	medium

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