SIOC_L2CAP_L2CA_GET_INFO: unvalidated info_size causes oversized kmalloc + feature non-functional
Summary
SIOC_L2CAP_L2CA_GET_INFO(:1061-1097): no upper-bound check on p->info_size(unlike PING:1002 which rejects >NG_L2CAP_MAX_ECHO_SIZE). NG_MKMESSAGE(...sizeof(*ip)+info_size...)(:1077) with M_WAITOK -> up to ~4GiB alloc. Request never populates trailing bytes. Downstream ng_l2cap_l2ca_get_info_req(ulpi.c:1435) rejects arglen!=sizeof(*ip) -> info_size>0 always fails. Memory-exhaustion DoS + non-functional GetInfo. Fix: clamp/reject info_size, alloc only sizeof(*ip).
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-0498 · 5 files| File | Type | Description | Size | |
|---|---|---|---|---|
| fix.diff | suggested-fix | Add an upper-bound check on info_size mirroring the PING path. | 490 B | view raw |
| VERDICT.md | verdict | source-confirmation + fix | 1.0 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-0498 — Low-severity source-confirmation
Verdict: REPRODUCED
Impact: dos Confidence: likely
Kernel ref: netgraph7/bluetooth/socket/ng_btsocket_l2cap_raw.c:1061
Mechanism / why
Source-confirmed: SIOC_L2CAP_L2CA_GET_INFO allocs sizeof(ip)+p->info_size with no upper bound, unlike the PING path (NG_L2CAP_MAX_ECHO_SIZE). Module-only (netgraph7).
Recommended fix
Add an upper-bound check on info_size mirroring the PING path.
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 dos; source-only confirmation)
Evidence (decisive lines)
DF-0498 [REPRODUCED] - netgraph7/bluetooth/socket/ng_btsocket_l2cap_raw.c:1061
PoC changes
fix.diff present in findings/poc/DF-0498/; batched into ../_batch_low/combined_all.patch
Verified recommended fix
Add an upper-bound check on info_size mirroring the PING path.
Verdict
Source-confirmed: SIOC_L2CAP_L2CA_GET_INFO allocs sizeof(ip)+p->info_size with no upper bound, unlike the PING path (NG_L2CAP_MAX_ECHO_SIZE). Module-only (netgraph7).
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