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# spectre-meltdown-checker
Spectre & Meltdown vulnerability/mitigation checker for Linux
Spectre & Meltdown Checker
==========================
A simple shell script to tell if your Linux installation is vulnerable
against the 3 "speculative execution" 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
Example of the output of the script:
Spectre and Meltdown mitigation detection tool v0.01
CVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'
* Kernel recompiled with LFENCE opcode insertion: UNKNOWN (check not yet implemented)
> STATUS: UNKNOWN (not implemented, but real answer is most probably VULNERABLE at this stage)
CVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'
* Mitigation 1
* Hardware (CPU microcode) support for mitigation: NO
* Kernel support for IBRS: NO
* IBRS enabled for Kernel space: NO
* IBRS enabled for User space: NO
* Mitigation 2
* Kernel recompiled with retpoline: UNKNOWN (check not yet implemented)
> STATUS: VULNERABLE (IBRS hardware + kernel support OR retpoline-compiled kernel are needed to mitigate the vulnerability)
CVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'
* Kernel supports Page Table Isolation (PTI): YES
* PTI enabled and active: YES
> STATUS: NOT VULNERABLE (PTI mitigates the vulnerability)