⬢ DragonFlyBSD Kernel Audit
DF-4040 / verdict.json
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{
  "finding_id": "DF-4040",
  "status": "inconclusive",
  "reproduced": 0,
  "impact": "none",
  "confidence": "certain",
  "verdict": "Source-certain NULL derefs, fiji DF-4006 / DF-3685 family on polaris: the V1 parser treats usMMDependencyTableOffset and usVddcLookupTableOffset as optional (mm table left NULL at process_pptables_v1_0.c:794-802, lookup at :281-288; parse result stays 0), but polaris10_init_smc_table unconditionally calls polaris10_populate_smc_vce_level (mm_table->count at polaris10_smumgr.c:1298), polaris10_populate_smc_uvd_level (:1404) and polaris10_populate_smc_voltage_tables -> polaris10_populate_cac_table (lookup_table->count at :712). Each faults on the NULL page during driver attach/resume -> kernel panic. Demonstrated (child SIGSEGV on the NULL deref): run.log DF-4040. Hardware-gated -> runtime inconclusive, source certain.",
  "exploit_chain": "crafted vBIOS PowerPlay table with usMMDependencyTableOffset==0 (or usVddcLookupTableOffset==0) -> parse OK -> polaris10_init_smc_table -> populate_* -> NULL->count page fault => panic",
  "evidence": "run.log section DF-4040 (child signal 11); VERDICT.md; fix_build.log; env.txt",
  "kernel_refs": [
    "sys/dev/drm/amd/powerplay/smumgr/polaris10_smumgr.c:1298",
    "sys/dev/drm/amd/powerplay/smumgr/polaris10_smumgr.c:1404",
    "sys/dev/drm/amd/powerplay/smumgr/polaris10_smumgr.c:712",
    "sys/dev/drm/amd/powerplay/hwmgr/process_pptables_v1_0.c:281",
    "sys/dev/drm/amd/powerplay/hwmgr/process_pptables_v1_0.c:794"
  ],
  "poc_changes": "Pass-2 reviewer authored demonstrator compiling the kernels own headers (smu74.h/smu74_discrete.h packed, or a verbatim copy of the drivers amdsentmsg/parsemsg arms) so struct geometry and branch selection are the kernels; fix.diff generated against the pristine file and compile-validated via full nativekernel rebuild on the guest (shared build with DF-4036..DF-4044, fix_build.log).",
  "attempts": 3,
  "guest_uname": "DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026 root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC x86_64",
  "runtime_sec": 200,
  "guest_dirty": 0,
  "build_cmd": "./build.sh",
  "run_cmd": "./run.sh",
  "code_hash": "a80c6d8179c5b51037b9b3c57bf5e23b8ff1b9791b667178a4b0fd8bf2b68475",
  "notes": "Hardware-gated (no Polaris GPU on guest; crafted-VBIOS threat model; amd-gpu absent per env.txt). Checklist kills: LinkLevel walk bounded (smu7_hwmgr.c:561-569 clamp), mc_reg walks not in this file, fan div0 = known DF-1345, VCE/UVD overflow = known DF-1346, Smio walks clamped.",
  "recommended_fix": "NULL-check mm_table in the VCE/UVD populators (return -EINVAL) and lookup_table in the CAC populator (fix.diff)",
  "fix_status": "fixed",
  "fix_baseline_reproduced": 0,
  "fix_patched_reproduced": 0,
  "fix_kernel_uname": "DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026 root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC x86_64 (nativekernel X86_64_GENERIC rebuilt with all DF-4036..DF-4044 patches; 0 errors under -Werror; see fix_build.log)",
  "fix_verdict": "fixed (compile-validated): all nine patches applied together to the clean guest /usr/src copy (polaris10_smumgr.c md5 6f39bb32..->19a2b278.., amd.c f577a330..->54ce1518..), make -j4 nativekernel KERNCONF=X86_64_GENERIC completed RC=0 with 0 compile errors under -Werror; the patched polaris10_smumgr.o (amdgpu module) and amd.o (GENERIC kernel) both recompiled. Runtime re-test impossible on this guest (device absent). Sources restored to pristine and md5-verified after validation.",
  "fix_evidence": "findings/poc/DF-4040/fix.diff; findings/poc/DF-4040/fix_build.log (build banner + compile lines + 0 errors)"
}