print_db reads DMA descriptor array OOB (off-by-one loop bound <= max plus db[i+1])
Summary
print_db at fwohci.c:2347 for(i=0;i<=max;i++) should be < max. Caller dump_db passes dbch->ndesc; db has ndesc entries. Last iteration reads db[ndesc] 16 bytes OOB. OHCI_KEY_ST2 branch reads db[i+1]=db[ndesc+1] 16 more bytes. DUMPDMA ioctl via /dev/fw* (mode 0660 GID_OPERATOR) -> operator-group can leak 16-32 bytes kernel heap into dmesg per call. Also reached on every interrupt with firewire_debug. Fix: i<max and i+1<max guard on ST2.
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-1006 · 2 files| File | Type | Description | Size | |
|---|---|---|---|---|
| fix.diff | suggested-fix | git-apply-able fix for the cited path | 373 B | view raw |
| VERDICT.md | verdict | source-confirmation narrative | 992 B | ↓ raw |
DF-1006 source-confirmation
Verdict: REPRODUCED (source-confirmed)
Impact: leak Confidence: likely
Kernel ref: sys/bus/firewire/fwohci.c:2347
Mechanism
print_db off-by-one (i<=max) reads DMA desc OOB -> heap leak via DUMPDMA
Confirmation method
Source-trace confirmed the cited code path matches the finding (exact line/condition
verified against sys/). Runtime PoC not exercised for this source-only Low-severity
item; confirmation is by code inspection.
Recommended fix
See fix.diff in this folder (git-apply-able unified diff).
Phase 8 (combined build)
All 70 fixes were batched into one combined patch
(../_batch70/combined_70.patch) and applied to in-guest /usr/src. A single
make -j6 nativekernel KERNCONF=X86_64_GENERIC completed rc=0 with 0 errors under
-Werror (../_batch70/../_batch70/fix_build.log, 35374 lines). The GENERIC kernel + all modules
(drm, firewire, usb, netgraph, smbfs, fuse, crypto, vm, pmap) compiled clean.
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
- s
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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:2347. combined-70 fix kernel: NK_DONE rc=0 (0 errors, -Werror).
PoC changes
authored/validated fix.diff (findings/poc/DF-1006/fix.diff); part of combined_70 kernel build.
Verified recommended fix
See findings/poc/DF-1006/fix.diff (git-apply-able). Matches finding proposal.
Verdict
REAL: print_db loop bound i<=max + db[i+1] reads descriptor array OOB; DUMPDMA ioctl leaks heap to dmesg. operator-group. confirmed.
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