DF-5318

USB_SETDEBUG sets the global usb_debug level with no privilege check (only FWRITE on the fd) — unprivileged kernel-log flooding / console spam

Summary

usb_debug = *(int*)addr gated only by FWRITE: any unpriv 'libusb user' floods console/serial with every USB event's DPRINTF (hw.usb.debug sysctl is root-only). SYSCAP_NODRIVER gate fix.

Discussion (0)

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Severity: Info
Status: new
Bucket: Privilege escalation (general use)
Confidence: likely
Pass: 2 · GLM 5.3 second pass
CVSS 3.1: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
CWE: CWE-862
File: sys/bus/u4b/usb_generic.c
Lines: 2084-2090
Area: hw
Discovered: 2026-10-02
Updated: 2026-10-02

Team triage

untriaged

priority: — · owner: —

PoC verification

untested

Status: untested
Reproduced: no
Impact: latent unchecked index (DF-5317) / unpriv log flooding (DF-5318)
Confidence: likely
Tested: 2026-10-02 15:40:35
Attempts: 0
Runtime: —
Code hash: —
Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0: Thu Jul 2 06:02:54 UTC 2026 root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC x86_64
Build cmd: n/a
Run cmd: n/a

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Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: no
Patched reproduced: no
Confidence: likely
Tested: 2026-10-02 15:40:35
Runtime: —
Kernel: per-fix-DF-5318
fix.diff: findings/poc/DF-5318/fix.diff
Runner: df-bsd-reviewer

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PoC verification

Evidence pack

findings/poc/DF-5318 · 1 files

File	Type	Description	Size
verdict.json	file		937 B	view raw

Fix verification

not_testable

baseline no→ patch + rebuild →patched clean

per-fix-DF-5318

Confirmed kernel references

sys/bus/u4b/usb_generic.c:2084

Detail

Evidence (decisive lines)

static trace (DF-5317 hunk included in findings/poc/DF-5314/fix.diff)

Verified recommended fix

see finding markdown

Verdict

untested (Info; latent union confusion / one-liner log-flood gate)