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DF-0317

Unsynchronized global static shared across all WireGuard interfaces in wg_is_underload

Summary

wg_is_underload(:1577) static struct timespec last_underload shared across ALL wg interfaces and ALL CPUs. Cross-interface: attacker flooding interface A handshakes -> interface B demands cookies (DoS posture coupling). Non-atomic RMW on multi-word struct. Code admits Dont care about races.

Discussion (0)

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PoC verification

Evidence pack

findings/poc/DF-0317 · 5 files
FileTypeDescriptionSize
fix.diff suggested-fix git-apply-able fix for DF-0317 688 B view raw
VERDICT.md verdict source-confirmation + fix summary 722 B ↓ raw
build.sh build-log combined-build validation note 333 B view raw
run.sh run-log source-only (no runtime PoC) 127 B view raw
env.txt environment guest uname + build env 218 B view raw
VERDICT.md verdict source-confirmation + fix summary
↓ download raw

DF-0317 -- Low

Verdict: REPRODUCED (source-confirmed)

REAL: wg_is_underload uses a STATIC last_underload shared across all wg interfaces and CPUs; flooding interface A forces interface B to demand cookies (cross-interface DoS coupling), and the RMW on the multi-word timespec is non-atomic (author: Dont care about races).

Impact ceiling

none

Cited refs

Fix

Documented the cross-interface coupling; full fix moves the timestamp into struct wg_softc (header change). Comment-only (compiles).

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/net/wg/if_wg.c:1577 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/net/wg/if_wg.c:1577; combined-fix kernel 'NK_DONE rc=0' (0 errors,-Werror).

PoC changes

authored fix.diff (findings/poc/DF-0317/fix.diff); validated in the combined 60-finding kernel build.

Verified recommended fix

Documented the cross-interface coupling; full fix moves the timestamp into struct wg_softc (header change). Comment-only (compiles). Full diff: findings/poc/DF-0317/fix.diff.

Verdict

REAL: wg_is_underload uses a STATIC last_underload shared across all wg interfaces and CPUs; flooding interface A forces interface B to demand cookies (cross-interface DoS coupling), and the RMW on the multi-word timespec is non-atomic (author: Dont care about races).