In the Linux kernel 4.19 through 5.6.7 on the s390 platform, code execution may occur because of a race condition, as demonstrated by code in enable_sacf_uaccess in arch/s390/lib/uaccess.c that fails to protect against a concurrent page table upgrade, aka CID-3f777e19d171. A crash could also occur.
git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=215d1f3928713d6eaec67244bcda72105b898000
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3f777e19d171670ab558a6d5e6b1ac7f9b6c574f
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3TZBP2HINNAX7HKHCOUMIFVQPV6GWMCZ/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AQUVKC3IPUC5B374VVAZV4J5P3GAUGSW/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZKVJMS4GQRH5SO35WM5GINCFAGXQ3ZW6/
security.netapp.com/advisory/ntap-20200608-0001/
usn.ubuntu.com/4342-1/
usn.ubuntu.com/4343-1/
usn.ubuntu.com/4345-1/
www.debian.org/security/2020/dsa-4667