spectre-meltdown-checker/README.md

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Spectre & Meltdown Checker
==========================
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A simple shell script to tell if your Linux installation is vulnerable against the 3 "speculative execution" CVEs.
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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.
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## Example of script output
![checker](https://framapic.org/FjroIZximyoM/EO5msoSMKb6L.png)
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## Quick summary of the CVEs
**CVE-2017-5753** bounds check bypass (Spectre Variant 1)
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- 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
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**CVE-2017-5715** branch target injection (Spectre Variant 2)
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- 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
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**CVE-2017-5754** rogue data cache load (Meltdown)
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- Impact: Kernel
- Mitigation: updated kernel (with PTI/KPTI patches), updating the kernel is enough
- Performance impact of the mitigation: low to medium