DF-0345

IP header checksum left stale after kernel records RR/TS options on locally-delivered packets

Summary

ip_dooptions modifies header when recording RR(:1702-1704)/TS(:1745-1771) options but never recomputes ip_sum. Forwarded packets repaired by ip_output. Locally delivered RR/TS packets: stale checksum. Transport layers use pseudo-header no re-verify ip_sum. Long-standing 4.4BSD behavior, no integrity bypass.

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Severity: Info
Status: new
Bucket: Base system — network stack
Confidence: certain
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U:C:N/I:N/A:N
CWE: CWE-998
File: sys/netinet/ip_input.c
Lines: 1702-1771
Area: net
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 18:17:11
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 18:17:11
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-0345/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-0345 · 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/netinet/ip_input.c:1702: IP header checksum left stale after recording RR/TS options

Verified recommended fix

Source-confirmed at sys/netinet/ip_input.c:1702: IP header checksum left stale after recording RR/TS options

Verdict

Source-confirmed at sys/netinet/ip_input.c:1702: IP header checksum left stale after recording RR/TS options