spectre-meltdown-checker/README.md

Spectre & Meltdown Checker

A simple shell script to tell if your Linux installation is vulnerable against the 3 “speculative execution” CVEs.

Without options, it’ll inspect you currently running kernel. You can also specify a kernel image on the command line, if you’d like to inspect a kernel you’re not running.

The script will do its best to detect mitigations, including backported non-vanilla patches, regardless of the advertised kernel version number.

Example of script output

checker

Quick summary of the CVEs

CVE-2017-5753 bounds check bypass (Spectre Variant 1)

• Impact: Kernel & all software
• Mitigation: recompile software and kernel with a modified compiler that introduces the LFENCE opcode at the proper positions in the resulting code
• Performance impact of the mitigation: negligible

CVE-2017-5715 branch target injection (Spectre Variant 2)

• Impact: Kernel
• Mitigation 1: new opcode via microcode update that should be used by up to date compilers to protect the BTB (by flushing indirect branch predictors)
• Mitigation 2: introducing “retpoline” into compilers, and recompile software/OS with it
• Performance impact of the mitigation: high for mitigation 1, medium for mitigation 2, depending on your CPU

CVE-2017-5754 rogue data cache load (Meltdown)

• Impact: Kernel
• Mitigation: updated kernel (with PTI/KPTI patches), updating the kernel is enough
• Performance impact of the mitigation: low to medium