DF-0913

fuse_audit_length / fuse_get_ops panic kernel on unknown opcode

Summary

fuse_util.c:230 fuse_panic(Invalid opcode) in fuse_audit_length default. :334 fuse_panic in fuse_get_ops default. fuse_panic -> panic() (debug.h:41-42). Opcode from kernel request header not attacker-controlled today. But any new fuse_abi.h opcode not added to switch = instant kernel panic on next FUSE operation. Fragile defense-in-depth. Fix: return -1 / return FUSE_UNKNOWN.

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Severity: Info
Status: new
Bucket: Base system — filesystems
Confidence: likely
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U:C:N/I:N/A:H
CWE: CWE-754 Improper Check
File: sys/vfs/fuse/fuse_util.c
Lines: 229-334
Area: vfs
Discovered: 2026-07-05
Updated: 2026-07-05

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: none
Confidence: likely
Tested: 2026-07-23 18:17:19
Attempts: —
Runtime: —
Code hash: —
Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0
Build cmd: —
Run cmd: —

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Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: yes
Patched reproduced: no
Confidence: likely
Tested: 2026-07-23 18:17:19
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-0913/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-0913 · 1 files

File	Type	Description	Size
manifest.json	file		389 B	view raw

Fix verification

not_testable

baseline reproduced→ patch + rebuild →patched clean

recommended fix identified; fix.diff not authored/validated in this batch

recommended fix identified; fix.diff not authored/validated in this batch

combined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Info severity)

Evidence (decisive lines)

Source-confirmed at sys/vfs/fuse/fuse_util.c:229: fuse_audit_length/fuse_get_ops panic kernel on unknown opcode

Verified recommended fix

Source-confirmed at sys/vfs/fuse/fuse_util.c:229: fuse_audit_length/fuse_get_ops panic kernel on unknown opcode

Verdict

Source-confirmed at sys/vfs/fuse/fuse_util.c:229: fuse_audit_length/fuse_get_ops panic kernel on unknown opcode