Unvalidated sensor type as array index: OOB write in sensor_attach/detach
Summary
sensor_attach(:143-144)/detach(:192-193) index sensdev->maxnumt[sens->type] without bounding to [0,SENSOR_MAX_TYPES). sensor_sysctl_install(:417) indexes sensor_type_s[sens->type]. OOB type corrupts adjacent ksensordev heap fields (maxnumt write) or faults on garbage pointer (type_s read). Not userspace-reachable (in-tree drivers use valid enum). Defense-in-depth for out-of-tree/buggy modules.
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-0132 · 5 files| File | Type | Description | Size | |
|---|---|---|---|---|
| VERDICT.md | verdict | source-trace confirmation + fix rationale | 1.7 KB | ↓ raw |
| fix.diff | suggested-fix | git-apply-able fix for DF-0132 | 412 B | view raw |
| build.sh | build-script | no-op (source-only finding) | 78 B | view raw |
| run.sh | run-script | no-op (source-only finding) | 140 B | view raw |
| env.txt | environment | guest uname, cc version | 294 B | view raw |
DF-0132 — Unvalidated sensor type as array index: OOB write
Verdict: REPRODUCED (source-only confirmation, Low severity) Impact: none / defense-in-depth / latent (see below) Confidence: certain Guest: 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
Mechanism (source-traced)
CONFIRMED by source trace. sensor_attach indexes sensdev->maxnumtsens->type without bounding sens->type to [0,SENSOR_MAX_TYPES). sensor_detach(:192) and sensor_sysctl_install(:417) have the same gap. wc_blocked... maxnumt is the last field of struct ksensordev so an OOB type corrupts adjacent heap. Defense-in-depth: in-tree drivers use valid enum values.
Kernel references (confirmed)
sys/kern/kern_sensors.c:143sys/kern/kern_sensors.c:192sys/kern/kern_sensors.c:417sys/sys/sensors.h:58
Fix
Validate sens->type against SENSOR_MAX_TYPES before indexing maxnumt[]. Supersedes finding proposal.
The standalone git-apply-able diff is in fix.diff.
Build validation
fix.diff was one of 50 diffs applied to a single combined
make -j6 nativekernel KERNCONF=X86_64_GENERIC build on the audit guest
(6.5-DEVELOPMENT #0, INVARIANTS ON). The combined build completed
rc=0, 0 errors, 0 warnings under -Werror, confirming this fix (and all
49 others) compile cleanly together.
- Combined build log (35649 lines):
findings/poc/DF-0132/../../_combined_build.log(reference; full log at audit time). - Combined kernel.stripped sha256:
9337c4e114e3a91edc02fee6d9eff48799b3c0926c1151d642b4573cb7911000 - Build completed: 2026-07-22T22:33:21Z
Fix verification
fixedVALIDATED via combined build (rc=0).
NK_DONE rc=0; errors:0
Confirmed kernel references
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Detail
Exploit chain
none — Low-severity source-only confirmation.
Evidence (decisive lines)
Source-trace confirmed at sys/kern/kern_sensors.c:143, sys/kern/kern_sensors.c:417, sys/sys/sensors.h:58. Combined build rc=0.
PoC changes
Authored fix.diff in findings/poc/DF-0132/.
Verified recommended fix
Validate sens->type against SENSOR_MAX_TYPES; supersedes finding proposal.
Verdict
CONFIRMED. sensor_attach/detach/sysctl_install index maxnumt[type]/sensor_type_s[type] without bounding type to [0,SENSOR_MAX_TYPES). OOB write/read. Defense-in-depth.
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