DF-0169

sysref_get has no refcount overflow guard

Summary

sysref_get (sysref2.h:68) atomic_add_int(&refcnt,1) unchecked. ~2^30 gets overflow INT_MAX -> negative -> _sysref_put KKASSERT panic or (no INVARIANTS) state corruption -> premature free/UAF. Infeasible: each ref consumes kernel memory, OOM first.

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Severity: Info
Status: new
Bucket: Kernel memory corruption (UAF / OOB write)
Confidence: certain
Pass: 1 · GLM 5.2 first 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-190
File: sys/kern/kern_sysref.c
Lines: 66-72
Area: kern
Discovered: 2026-06-30
Updated: 2026-06-30

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: none
Confidence: certain
Tested: 2026-07-23 18:17:05
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: certain
Tested: 2026-07-23 18:17:05
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-0169/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-0169 · 1 files

File	Type	Description	Size
manifest.json	file		387 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/kern/kern_sysref.c:66: sysref_get has no refcount overflow guard

Verified recommended fix

Source-confirmed at sys/kern/kern_sysref.c:66: sysref_get has no refcount overflow guard

Verdict

Source-confirmed at sys/kern/kern_sysref.c:66: sysref_get has no refcount overflow guard