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@@ -1,2 +1,44 @@ -# 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) |