⬢ DragonFlyBSD Kernel Audit
DF-4008 / verdict.json
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{
  "finding_id": "DF-4008",
  "status": "inconclusive",
  "reproduced": 0,
  "impact": "none",
  "confidence": "likely",
  "verdict": "Mechanism certain at source level, hardware-gated live: mpr_diag_register() overwrites the single shared fw_diag_{dmat,buffer,map,busaddr} trio without checking it is free, while per-type fw_diag_buffer_list[].size keeps the stale (larger) size; with two diag types enabled by the IOC (mpr.c:588-599 enables every advertised capability) an ioctl user gets (1) a stale-size OOB copyout (kernel disclosure up to first-registration size minus live size), (2) a cross-type free of the other types DMA resources, (3) a NULL-dmat bus_dmamap_sync panic or UAF read on the next READ_BUFFER. Deterministic, no race (serialized by MPR_FLAGS_BUSY). No LSI SAS controller on the audit guest, so not live-reproduced; verbatim userspace replication on the guest shows all three transitions (1,044,480-byte OOB disclosure figure, cross-free, NULL-deref point).",
  "exploit_chain": "operator-group ioctl user: REGISTER(TRACE,1MB) -> REGISTER(SNAPSHOT,4KB) -> READ_BUFFER(uidTRACE,0,1MB) discloses ~1MB past a 4KB DMA allocation to userspace; UNREGISTER(uidTRACE) frees SNAPSHOTs resources; READ_BUFFER(uidSNAPSHOT) panics (bus_dmamap_sync(NULL), mpr_user.c:1805) or reads freed memory.",
  "evidence": "replication_run.log (all five steps with the three failure shapes printed), diag_statemachine.c (verbatim port of mpr_diag_register/unregister/read_buffer modulo bus_dma stubs), VERDICT.md root-cause path:line trace",
  "kernel_refs": [
    "sys/dev/raid/mpr/mpr_user.c:1504",
    "sys/dev/raid/mpr/mpr_user.c:1508",
    "sys/dev/raid/mpr/mpr_user.c:1523",
    "sys/dev/raid/mpr/mpr_user.c:1596",
    "sys/dev/raid/mpr/mpr_user.c:1612",
    "sys/dev/raid/mpr/mpr_user.c:1681",
    "sys/dev/raid/mpr/mpr_user.c:1798",
    "sys/dev/raid/mpr/mpr_user.c:1805",
    "sys/dev/raid/mpr/mpr_user.c:1812",
    "sys/dev/raid/mpr/mprvar.h:410",
    "sys/dev/raid/mpr/mprvar.h:440",
    "sys/dev/raid/mpr/mpr.c:588"
  ],
  "poc_changes": "n/a (new finding; replication authored during pass 2)",
  "attempts": 1,
  "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": 60,
  "guest_dirty": 0,
  "build_cmd": "cd /tmp && cc -O2 -Wall -o diag_statemachine diag_statemachine.c",
  "run_cmd": "/tmp/diag_statemachine",
  "code_hash": "sha256: see diag_statemachine.c",
  "notes": "Privileged surface (0640 root:operator). Impact ceiling: kernel heap disclosure + panic/DoS; no write primitive in this path. Live trigger needs FW accepting DIAG_BUFFER_POST and advertising >=2 diag types.",
  "recommended_fix": "Make the diag DMA trio per-type inside mpr_fw_diagnostic_buffer_t (or refuse REGISTER while sc->fw_diag_buffer is live); bound READ_BUFFER against the live allocation size.",
  "fix_status": "untested",
  "fix_baseline_reproduced": 0,
  "fix_patched_reproduced": 0,
  "fix_verdict": "fix.diff not yet authored for this finding (see VERDICT.md sketch: per-type dmat/map/buffer/busaddr fields)",
  "fix_evidence": ""
}