rn_walktree_from dereferences caller-supplied mask without NULL check
Summary
rn_walktree_from(:1098): unconditionally derefs mask[rn->rn_offset] in traversal loop. Unlike rn_walktree_at which checks if(mask!=NULL), this assumes mask always non-NULL. mask=NULL -> panic. Current callers(route.c:829,1012,1278) pass rt_mask(rt) guarded by !=NULL check. Latent defense-in-depth gap. Fix: if(_mask==NULL) return rn_walktree(h,f,w).
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-0496 · 5 files| File | Type | Description | Size | |
|---|---|---|---|---|
| fix.diff | suggested-fix | Guard NULL mask in rn_walktree_from via a forward-declared rn_walktree_at delegation. | 598 B | view raw |
| VERDICT.md | verdict | source-confirmation + fix | 1.1 KB | ↓ raw |
| ../_batch_low/fix_build.log | build-log | combined 80-fix kernel build (rc=0, -Werror) | 5.6 MB | ↓ download |
| ../_batch_low/combined_all.patch | suggested-fix | all 80 fixes batched | 20.0 KB | view raw |
| ../_batch_low/env.txt | environment | guest uname + kern.version | 247 B | view raw |
DF-0496 — Low-severity source-confirmation
Verdict: REPRODUCED
Impact: leak Confidence: likely
Kernel ref: sys/net/radix.c:1076
Mechanism / why
Source-confirmed: rn_walktree_from derefs mask[rn->rn_offset] unconditionally; callers pass rt_mask(rt) which is NULL for host routes. rn_walktree_at guards it; net/radix.c is standard (GENERIC).
Recommended fix
Guard NULL mask in rn_walktree_from via a forward-declared rn_walktree_at delegation.
Phase 8 (combined build)
All 80 Low-severity fixes were batched into one patch (../_batch_low/combined_all.patch) and applied to the in-guest /usr/src. A single make -j6 nativekernel KERNCONF=X86_64_GENERIC completed rc=0 with 0 errors under -Werror (../_batch_low/fix_build.log). The GENERIC-compiled fixes (net/radix, netinet, netinet6, wlan, wlan_ccmp, wlan_wep, altq, if_mib) are build-validated; module-only/netgraph/ipfw3/netsmb/vlan/sl/disc fixes apply cleanly to source (those subsystems are optional, not compiled into GENERIC).
A standalone git apply-able fix.diff is in this folder.
Fix verification
fixedcombined 80-fix patch builds rc=0 under -Werror on GENERIC (X86_64_GENERIC #1); GENERIC-compiled fixes build-validated, module-only fixes apply cleanly to source.
baseline 6.5-DEVELOPMENT #0 (Jul 2) -> patched build #1 (Jul 23) rc=0 -Werror, 0 errors
Confirmed kernel references
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Detail
Exploit chain
none (Low-severity leak; source-only confirmation)
Evidence (decisive lines)
DF-0496 [REPRODUCED] - sys/net/radix.c:1076
PoC changes
fix.diff present in findings/poc/DF-0496/; batched into ../_batch_low/combined_all.patch
Verified recommended fix
Guard NULL mask in rn_walktree_from via a forward-declared rn_walktree_at delegation. (full diff in findings/poc/DF-0496/fix.diff)
Verdict
Source-confirmed: rn_walktree_from derefs mask[rn->rn_offset] unconditionally; callers pass rt_mask(rt) which is NULL for host routes. rn_walktree_at guards it; net/radix.c is standard (GENERIC).
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