darknet-cfg-layerindex-oob-poc

PoC — Darknet shortcut/route layer index OOB net.layers[] access

huntr MFV PoC vs hank-ai/darknet src-lib/darknet_cfg.cpp. Authorized security research (responsible disclosure via huntr).

parse_shortcut_section (darknet_cfg.cpp:1773-1783) uses the .cfg from= index to subscript net.layers[] with no bounds check; parse_route_section (:1534-1548) checks only the upper bound (route_index >= parms.index), omitting the lower bound, so negative indices pass. A malicious .cfg (loaded alongside .weights) with from=2000000000 (or a large negative) causes a wild OOB access of net.layers[index] at load — SIGSEGV, plus propagation of wild .output/.delta pointers into the shortcut layer's forward pass.

Files

• poc_shortcut_oob.cfg — malicious Darknet config ([shortcut] from=2000000000).
• layerindex_repro.c / CRASH_PROVEN.md — isolated repro; EXC_BAD_ACCESS at net.layers[index].

Reproduce

cc -O0 -g layerindex_repro.c -o layerindex_repro && ./layerindex_repro 2000000000   # -> SIGSEGV
# end-to-end: load poc_shortcut_oob.cfg with darknet -> crash in parse_shortcut_section.

Fix

Bound-check index/route_index to [0, net.n) (or [0, parms.index)) in parse_shortcut_section and add the missing route_index < 0 check in parse_route_section.