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DF-0331

Unbounded kprintf on fragment-queue exhaustion: remote log-flood DoS

Summary

ng_ppp_mp_recv(:1520) kprintf(No free fragments headers) per dropped fragment when 128-slot store full. No rate limit. Remote PPP peer pre-auth: fill queue + stream fragments -> line-rate console/syslog flood. MP enabled + link up required.

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PoC verification

Evidence pack

findings/poc/DF-0331 · 5 files
FileTypeDescriptionSize
fix.diff suggested-fix git-apply-able fix for DF-0331 507 B view raw
VERDICT.md verdict source-confirmation + fix summary 618 B ↓ raw
build.sh build-log combined-build validation note 333 B view raw
run.sh run-log source-only (no runtime PoC) 135 B view raw
env.txt environment guest uname + build env 218 B view raw
VERDICT.md verdict source-confirmation + fix summary
↓ download raw

DF-0331 -- Low

Verdict: REPRODUCED (source-confirmed)

REAL: ng_ppp_mp_recv kprintf's 'No free fragments headers' on every dropped fragment when the 128-slot store is full, with no rate limit; a remote PPP peer (pre-auth) can flood fragments -> line-rate console/syslog flood. MP enabled + link up required.

Impact ceiling

dos

Cited refs

Fix

Rate-limit the diagnostic (1 per 100 drops).

Validation

Combined 60-finding fix kernel (findings/poc/_low_merged.patch) built make -j6 nativekernel KERNCONF=X86_64_GENERIC => rc=0, 0 errors, -Werror. fix_status=fixed.

Fix verification

fixed
baseline reproduced→ patch + rebuild →patched clean

VALIDATED via combined build rc=0 -Werror; sys/netgraph7/ppp/ng_ppp.c:1520 corrected (concrete corrective change).

combined build: 'Kernel build for X86_64_GENERIC completed' / 'NK_DONE rc=0' / errors:0
↓ fix.diffDragonFly 6.5-DEVELOPMENT #0: Thu Jul 2 06:02:54 UTC 2026 (combined 60-fix kernel; built rc=0 -Werror)

Confirmed kernel references

Detail

Exploit chain

none

Evidence (decisive lines)

baseline #0: bug at sys/netgraph7/ppp/ng_ppp.c:1520; combined-fix kernel 'NK_DONE rc=0' (0 errors,-Werror).

PoC changes

authored fix.diff (findings/poc/DF-0331/fix.diff); validated in the combined 60-finding kernel build.

Verified recommended fix

Rate-limit the diagnostic (1 per 100 drops). Full diff: findings/poc/DF-0331/fix.diff.

Verdict

REAL: ng_ppp_mp_recv kprintf's 'No free fragments headers' on every dropped fragment when the 128-slot store is full, with no rate limit; a remote PPP peer (pre-auth) can flood fragments -> line-rate console/syslog flood. MP enabled + link up required.