Related Vulnerabilities: CVE-2017-17862  

It has been discovered that kernel/bpf/verifier.c in the Linux kernel before 4.14.9 and 4.9.72 ignore unreachable code, even though it would still be processed by JIT compilers. This behavior, also considered an improper branch-pruning logic issue, could possibly be used by local users for denial of service.

Severity Medium

Remote No

Type Denial of service

Description

It has been discovered that kernel/bpf/verifier.c in the Linux kernel before 4.14.9 and 4.9.72 ignore unreachable code, even though it would still be processed by JIT compilers. This behavior, also considered an improper branch-pruning logic issue, could possibly be used by local users for denial of service.

AVG-574 linux-hardened 4.14.7.a-1 4.14.11.a-1 High Fixed FS#56832

AVG-571 linux-zen 4.14.7-1 4.14.11-1 High Fixed FS#56832

AVG-561 linux-lts 4.9.68-1 4.9.74-1 High Fixed

AVG-552 linux 4.14.7-1 4.14.11-1 High Fixed FS#56832

05 Jan 2018 ASA-201801-4 AVG-574 linux-hardened High multiple issues

05 Jan 2018 ASA-201801-3 AVG-571 linux-zen High multiple issues

05 Jan 2018 ASA-201801-2 AVG-561 linux-lts High multiple issues

05 Jan 2018 ASA-201801-1 AVG-552 linux High multiple issues

https://bugs.chromium.org/p/project-zero/issues/detail?id=1454
http://www.openwall.com/lists/oss-security/2017/12/21/2
https://git.kernel.org/linus/c131187db2d3fa2f8bf32fdf4e9a4ef805168467

Workaround by disabling unprivileged bpf:
sysctl -w kernel.unprivileged_bpf_disabled=1