CVE-2020-11884

A flaw was found in the Linux kernel on s390 architecture. The issue occurs on multiprocessing systems when one s390 CPU is in Secondary Address Mode and another CPU does a kernel page table upgrade. An inter-processor interrupt (IPI) is then sent to each active CPU to update the control registers with new page table addresses. In Secondary Address Mode the CPU's CR1 register may hold kernel space address to fetch instructions from, but after IPI processing, the same CR1 register is set to point to a user space address. An unprivileged user or process on the system may use this flaw to crash the system or escalate their privileges on the system. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

This issue does not affect the versions of the kernel package as shipped with the Red Hat Enterprise Linux 5, 6, 7, and Red Hat Enterprise MRG 2.

This issue affects the versions of the kernel package as shipped with the Red Hat Enterprise Linux 8. Future kernel updates for the Red Hat Enterprise Linux 8 may address this issue.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update as soon as possible.