An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service because of bad continuation handling in GNTTABOP_copy. Grant table operations are expected to return 0 for success, and a negative number for errors. The fix for CVE-2017-12135 introduced a path through grant copy handling where success may be returned to the caller without any action taken. In particular, the status fields of individual operations are left uninitialised, and may result in errant behaviour in the caller of GNTTABOP_copy. A buggy or malicious guest can construct its grant table in such a way that, when a backend domain tries to copy a grant, it hits the incorrect exit path. This returns success to the caller without doing anything, which may cause crashes or other incorrect behaviour.

Affected: Ubuntu:20.04:LTS: xen

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 Monné discovered that Xen incorrectly handled caching on x86 Intel systems. An a…