{"id":15924609,"url":"https://github.com/nstarke/instrfuzz","last_synced_at":"2025-06-12T16:38:56.207Z","repository":{"id":230473221,"uuid":"779473052","full_name":"nstarke/instrfuzz","owner":"nstarke","description":"A CPU Instruction Fuzzer for QEMU x86","archived":false,"fork":false,"pushed_at":"2024-04-08T15:06:32.000Z","size":33,"stargazers_count":10,"open_issues_count":0,"forks_count":1,"subscribers_count":3,"default_branch":"main","last_synced_at":"2025-04-04T22:23:12.617Z","etag":null,"topics":["assembly","fuzzer","x86"],"latest_commit_sha":null,"homepage":"","language":"Assembly","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"mit","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/nstarke.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":"LICENSE","code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2024-03-29T23:16:53.000Z","updated_at":"2024-09-29T18:51:38.000Z","dependencies_parsed_at":"2024-04-08T16:40:22.015Z","dependency_job_id":null,"html_url":"https://github.com/nstarke/instrfuzz","commit_stats":null,"previous_names":["nstarke/instrfuzz"],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/nstarke/instrfuzz","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/nstarke%2Finstrfuzz","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/nstarke%2Finstrfuzz/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/nstarke%2Finstrfuzz/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/nstarke%2Finstrfuzz/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/nstarke","download_url":"https://codeload.github.com/nstarke/instrfuzz/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/nstarke%2Finstrfuzz/sbom","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":259503049,"owners_count":22867917,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["assembly","fuzzer","x86"],"created_at":"2024-10-06T21:23:01.970Z","updated_at":"2025-06-12T16:38:56.187Z","avatar_url":"https://github.com/nstarke.png","language":"Assembly","funding_links":[],"categories":[],"sub_categories":[],"readme":"# Instrfuzz\n\nThis is an x86 CPU instruction fuzzer. I built this to test for CPU-level bugs using QEMU.  \n\n## Prior Art\n\nA much better x86 CPU instruction fuzzer is [sandsifter](https://github.com/xoreaxeaxeax/sandsifter).  Sandsifter inspired this project\n\n## Install Dependencies\n\nUse your package manager of choice to install:\n\n* `qemu-system`\n* `nasm`\n\nFor example, for Debian-based distributions:\n\n```\nsudo apt install qemu-system nasm\n```\n\nFor macOS:\n\n```\nbrew install qemu-system nasm\n```\n\n## How to run\n\nClone the repository and then run `bash instrfuzz.sh` in the newly cloned repository directory\n\n## Bugs?\n\nThe following CPU instructions result in anoymalous behavior:\n\n```\n0xF541C7A7 ; 0x909090C7 works too.  Something with the '0xc7' opcode.\n0x0C1EDFF7\n0x4FFC09F5\n0x03AEDFF7\n0x39F0F650 ; this one causes a segfault in QEMU\n0xA7F03DF0 ; crashes qemu / illegal instruction coredump in elf\n0xEA413CA0 ; not even sure what is going on with this.\n0x2BD93390\n```\n\n## Triaging\n\nThere are two scripts that can be used to triage fuzzer results:\n\n* `test-instruction.sh $INSN`\n* `test-elf.py $INSN`\n\n`test-instruction.sh` will test the instruction as part of the MBR, which means no memory protections or operating system protections are in place\n\n* `test-elf.py $INSN` will test the instruction as part of a elf file linked with GLIBC.  I would never run this script as root :-)\n\nFor example, try running this shell one-liner:\n\n```\n./`python3 elf-test.py 0x39F0F650`\n```\n\nThis will create a .elf file and then execute that .elf file (the elf filename/path is printed to stdout after the sub shell command is run)","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fnstarke%2Finstrfuzz","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fnstarke%2Finstrfuzz","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fnstarke%2Finstrfuzz/lists"}