DF-4959

's' blink-spec filter typo `*s <= 'u'` accepts arbitrary characters as no-op blink ticks

Summary

The <= makes any char <= 'u' pass the filter as a no-op tick (masks the simplest DF-4958 trigger). Inherited from FreeBSD. One-character == fix.

Discussion (0)

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Severity: Info
Status: new
Bucket: Base system — drivers
Confidence: certain
Pass: 2 · GLM 5.3 second pass
CVSS 3.1: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:N
CWE: CWE-20
File: sys/dev/misc/led/led.c
Lines: 169-174
Area: dev
Discovered: 2026-09-25
Updated: 2026-09-25

Team triage

untriaged

priority: — · owner: —

PoC verification

untested

Status: untested
Reproduced: no
Impact: none
Confidence: certain
Tested: 2026-09-25 11:00:23
Attempts: 0
Runtime: —
Code hash: —
Guest: —
Build cmd: —
Run cmd: —

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Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: —
Patched reproduced: —
Confidence: certain
Tested: 2026-09-25 11:00:24
Runtime: —
Kernel: per-fix-DF-4959
fix.diff: findings/poc/DF-4959/fix.diff
Runner: df-bsd-reviewer

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PoC verification

Evidence pack

findings/poc/DF-4959 · 1 files

File	Type	Description	Size
verdict.json	file		726 B	view raw

Fix verification

not_testable

per-fix-DF-4959

Confirmed kernel references

sys/dev/misc/led/led.c:169-174

Detail

Exploit chain

none - functional filter semantics

Evidence (decisive lines)

findings/poc/DF-4959/ (this verdict)

Verdict

Functional (Info; inherited from FreeBSD): the 's' blink-spec filter reads s == 'U' || s <= 'u' - the <= makes ANY char <= 'u' (all control chars, digits, k-u, and via signed char every high-bit byte) pass as a no-op blink tick. Masks the simplest DF-4958 trigger. Interpreter branches all range-bounded - no memory-safety impact. One-character == fix (upstream too).