engineering/java-topology
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

vlc+obs-studio: CWE-407 scan — 2 defects (vlc-0001 randomizer_Remove O(N×C), obs-studio-0001 push_audio_tree da_find O(N²)/frame)

Browse source
This commit is contained in:
russell@unturf.com 2026-03-30 11:33:01 -04:00
parent 860b0ee52e
commit 15a65b2227
4 changed files with 271 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

38
defects/obs-studio/patch/obs-studio-0001-audio-render-order-linear-scan.patch Normal file
View file

@ -0,0 +1,38 @@
# UNDF: (leave blank)
# CWE-407: Algorithmic Complexity — push_audio_tree da_find O(N²) per frame
#
# push_audio_tree() and push_audio_tree2() use da_find(audio->render_order,
# &source, 0) which is a linear scan O(N) of the render_order darray.
# These callbacks are invoked via obs_source_enum_active_tree() for every
# source in the audio scene graph. With N sources, building the render
# order is O(N²) — and this runs every audio frame (~47 Hz at 48 kHz).
#
# Fix: maintain a pointer hash set alongside render_order for O(1)
# membership checks, or use a 'visited' flag on obs_source_t cleared
# at the start of each audio tick.
#
# Severity: HIGH (hot audio path, runs ~47 times/second, quadratic in
# active source count — noticeable with complex scenes)
# Measured: 250× op-count ratio at N=500 sources
#
--- a/libobs/obs-audio.c
+++ b/libobs/obs-audio.c
@@ -30,7 +30,8 @@ static void push_audio_tree(obs_source_t *parent, obs_source_t *source, void *p)
{
struct obs_core_audio *audio = p;
- if (da_find(audio->render_order, &source, 0) == DARRAY_INVALID) {
+ /* TODO: replace da_find O(N) linear scan with hash set for O(1) lookup.
+ * Current code is O(N²) per audio frame when N sources are active. */
+ if (da_find(audio->render_order, &source, 0) == DARRAY_INVALID) {
obs_source_t *s = obs_source_get_ref(source);
if (s) {
da_push_back(audio->render_order, &s);
@@ -59,7 +60,8 @@ static void push_audio_tree2(obs_source_t *parent, obs_source_t *source, void *p
struct obs_core_audio *audio = p;
- size_t idx = da_find(audio->render_order, &source, 0);
+ /* TODO: replace da_find O(N) with hash set for O(1) lookup */
+ size_t idx = da_find(audio->render_order, &source, 0);
if (idx == DARRAY_INVALID) {