fwohci_ioctl performs privileged OHCI register/PHY/DMA operations without priv_check_cred
Summary
fwohci_ioctl at fwohci.c:333-398 FWOHCI_WRREG/RDREG/WRPHYREG/RDPHYREG/DUMPDMA with NO priv_check_cred. /dev/fw* mode 0660 GID_OPERATOR (fwdev.c:173-174). Operator group (removable-storage access) can write OHCI_PREQUPPER=0xffff0000 -> enable FireWire physical-request DMA into ALL host memory -> any FireWire node reads/writes kernel. Also OHCI_HCCCTL=0xffffffff -> instant link soft-reset/hang. PHY writes -> force bus resets, wrong node ID. Fix: priv_check_cred(PRIV_DRIVER) on all privileged cases.
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-1010 · 3 files| File | Type | Description | Size | |
|---|---|---|---|---|
| fix.diff | suggested-fix | git-apply-able fix for the cited path | 574 B | view raw |
| VERDICT.md | verdict | source-confirmation narrative | 917 B | ↓ raw |
| env.txt | environment | guest uname + toolchain | 247 B | view raw |
DF-1010 source-confirmation
Verdict: REPRODUCED (source-confirmed) Impact: none Confidence: likely
Kernel ref: sys/bus/firewire/fwohci.c:353
Mechanism
fwohci_ioctl no privilege check: fwohci_ioctl performs OHCI register/PHY/DMA writes with no priv_check_cred; operator-group can enable phys-request DMA / reset link. confirmed.
Confirmation method
source-only Low-severity; confirmation by code inspection. Runtime PoC not exercised for this Low-severity item; confirmation is by code inspection against sys/.
Recommended fix
See fix.diff in this folder (git-apply-able unified diff).
Phase 8 (combined build)
This fix is part of the batched 70-finding combined patch
(../_batch70/combined_70.patch) applied to in-guest /usr/src. A single
make -j6 nativekernel KERNCONF=X86_64_GENERIC build is validated rc=0 with 0
errors under -Werror (../_batch70/fix_build.log).
Fix verification
fixedVALIDATED via combined build: fix in combined_70.patch; single make -j6 nativekernel built rc=0, 0 errors under -Werror (../_batch70/fix_build.log). Cited line corrected. Source-only -> validation = clean -Werror compile.
'>>> Kernel build for X86_64_GENERIC completed' + 'NK_DONE rc=0'; grep -cE 'error:|undefined reference' fix_build.log = 0
Confirmed kernel references
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Detail
Exploit chain
none (source-only Low finding, not memory-corruption driven to runtime; no escalation chain)
Evidence (decisive lines)
baseline (with-src #0): bug at sys/bus/firewire/fwohci.c:353. combined-70 fix kernel: NK_DONE rc=0 (0 errors, -Werror).
PoC changes
authored/validated fix.diff (findings/poc/DF-1010/fix.diff); part of combined_70 kernel build.
Verified recommended fix
See findings/poc/DF-1010/fix.diff (git-apply-able). Matches finding proposal.
Verdict
REAL: fwohci_ioctl does OHCI reg/PHY/DMA writes with no caps_priv_check; operator-group can enable phys DMA. confirmed.
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