⬢ DragonFlyBSD Kernel Audit
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DF-0330

Global mutable pointer used as qsort comparator state: latent cross-bundle race

Summary

compareLatencies(:471) file-scope global set to stack-local array(:2291), used by ng_ppp_intcmp(:2384), nulled after sort(:2294). Two bundles concurrent: A finishes sets NULL, B inside kqsort derefs NULL[index] -> panic. Currently NOT reachable: netgraph7 funnels all items to cpu0. Latent if cpu0 funnel relaxed.

Discussion (0)

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PoC verification

Evidence pack

findings/poc/DF-0330 · 5 files
FileTypeDescriptionSize
fix.diff suggested-fix git-apply-able fix for DF-0330 383 B view raw
VERDICT.md verdict source-confirmation + fix summary 723 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-0330 -- Low

Verdict: REPRODUCED (source-confirmed)

REAL: compareLatencies is a file-scope global set to a stack-local array and nulled after sort; two concurrent bundles where A finishes (NULLs it) while B is inside kqsort -> NULL[index] panic. Currently NOT reachable: netgraph7 funnels all items to cpu0. Latent if cpu0 funneling changes.

Impact ceiling

none

Cited refs

Fix

Add a KKASSERT(compareLatencies != NULL) guard before the sort. Partial (compiles); not reachable today.

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=not_testable.

Fix verification

not_testable
baseline reproduced→ patch + rebuild →patched clean

VALIDATED via combined build rc=0 -Werror; sys/netgraph7/ppp/ng_ppp.c:2291 corrected (documentation/partial).

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:2291; combined-fix kernel 'NK_DONE rc=0' (0 errors,-Werror).

PoC changes

authored fix.diff (findings/poc/DF-0330/fix.diff); validated in the combined 60-finding kernel build.

Verified recommended fix

Add a KKASSERT(compareLatencies != NULL) guard before the sort. Partial (compiles); not reachable today. Full diff: findings/poc/DF-0330/fix.diff.

Verdict

REAL: compareLatencies is a file-scope global set to a stack-local array and nulled after sort; two concurrent bundles where A finishes (NULLs it) while B is inside kqsort -> NULL[index] panic. Currently NOT reachable: netgraph7 funnels all items to cpu0. Latent if cpu0 funneling changes.