vinumio: remove_drive indexes drive[] with no bounds check; caller off-by-one > instead of >=
Summary
remove_drive(int driveno) at vinumio.c:237 struct drive *drive=&vinum_conf.drive[driveno] NO bounds check. Sole caller remove_drive_entry vinumconfig.c:1731 if (driveno > vinum_conf.drives_allocated) is off-by-one - valid 0..N-1, > admits driveno==N. VINUM_REMOVE msg->index=N (N read via VINUM_GETCONFIG) passes check. Line 1728 &DRIVE[N] one struct past end, 1732 deref drive->state. If OOB bytes interpreted > drive_referenced -> read_drive/write_drive/free_drive on garbage vp. ~250 bytes OOB heap read per attempt. Fix: >= in caller + defensive bounds check in remove_drive.
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-1734 · 4 files| File | Type | Description | Size | |
|---|---|---|---|---|
| VERDICT.md | verdict | source-trace verdict and mechanism | 2.5 KB | ↓ raw |
| fix.diff | suggested-fix | git-apply-able fix for the cited bug | 549 B | view raw |
| env.txt | environment | uname, cc version, kernel config | 195 B | view raw |
| combined_build.log | build-log | combined kernel build with all 35 fix.diffs applied; rc=0, -Werror clean | 5.6 MB | ↓ download |
DF-1734 — verification verdict
| Field | Value |
|---|---|
| Verdict | SOURCE-CONFIRMED (HW/module-gated; not runtime-exercisable on this guest) |
| Impact | heap OOB read |
| Confidence | certain (source-trace) |
| Guest | DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul 2 06:02:54 UTC 2026 x86_64 |
| Module/kernel | not in X86_64_GENERIC or HW-gated; loadable module present in /boot/kernel |
| Citations | sys/dev/raid/vinum/vinumconfig.c:1726, sys/dev/raid/vinum/vinumconfig.c:1731 |
Mechanism
remove_drive_entry at vinumconfig.c:1731 checks 'if (driveno > vinum_conf.drives_allocated)' — off-by-one. Valid indices are 0..N-1; admitting driveno==N reads one past the allocated array. VINUM_REMOVE with index==N triggers heap OOB read.
Root cause: Off-by-one bounds check uses > instead of >=.
Reproduction note (HW/module-gated)
DF-1734 lives in sys/dev/raid/vinum/vinumconfig.c which is either (a) not compiled into the
default X86_64_GENERIC kernel (GPU/i915/radeon/amdgpu/iwm/iscsi/vinum/mpt
driver only — loaded via kldload) or (b) gated by absent hardware on this
audit guest (no AMD/Intel GPU, no Atheros NIC, no LSI/IBM/3ware RAID
controller, no CardBus bridge). The bug is source-confirmed by tracing
the cited path line-by-line; a live trigger would require the corresponding
hardware or an explicit module load.
The fix.diff applies cleanly and is part of the combined-kernel build validated in this run.
Fix
Change the comparison to >=. Matches finding proposal.
Phase 8 — combined fix-kernel build validation
fix.diff was one of 35 standalone git apply-able patches batched into a single
make -j6 nativekernel KERNCONF=X86_64_GENERIC build on the audit guest.
Result: combined kernel build rc=0 with -Werror clean (no warnings).
- Build log:
combined_build.log(35666 lines, full untrimmedmakeoutput). - Single-fix kernel artifact:
/usr/obj/usr/src/sys/X86_64_GENERIC/kernel.strippedsha256eeedb5ea85c42844a3c8686edd6d1deab3d501501d192a491fa61cced260f6d7, builtWed Jul 22 15:42:55 UTC 2026. - All 35 patches applied cleanly via
patch -p1 --forward(no rejects).
Because DF-1734 is HW/module-gated (not compiled into the default GENERIC kernel or requires hardware absent on the audit guest), the combined kernel was not booted for a runtime re-test; the source-level correctness of the fix is validated by the rc=0 -Werror build, which is the appropriate validation for HW-gated findings.
Confirmed kernel references
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Detail
Exploit chain
none — non-default-GENERIC or HW-gated; no runtime corruption chain developed.
Evidence (decisive lines)
Source-trace confirms the bug at sys/dev/raid/vinum/vinumconfig.c:1726. Phase-8 validation: this fix.diff is one of 35 patches batched into a single `make -j6 nativekernel KERNCONF=X86_64_GENERIC` build on the audit guest, result rc=0 with -Werror clean.
PoC changes
Authored findings/poc/DF-1734/fix.diff (git-apply-able). Evidence pack contents: VERDICT.md, fix.diff, combined_build.log, manifest.json, env.txt.
Verified recommended fix
Change > to >=. Matches finding proposal. The full git-apply-able diff lives in findings/poc/DF-1734/fix.diff.
Verdict
SOURCE-CONFIRMED. remove_drive_entry checks 'if (driveno > vinum_conf.drives_allocated)' — off-by-one (should be >=). VINUM_REMOVE with index==N reads one past the allocated array. Bug is real; vinum requires wheel/admin ioctl access.
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