AudioReactive Palettes inconsistent / unsafe behaviour when switching off the usermod temporarily

[softhack007]

WLED/usermods/audioreactive/audio_reactive.cpp

Lines 1958 to 1960 in 4efb02d

	// add/remove custom/audioreactive palettes
	if (prevEnabled && !enabled) removeAudioPalettes();
	if (!prevEnabled && enabled) createAudioPalettes();

When the AR usermod is "switched off" (button in info panel, or by unchecking "enabled" in AR settings). audioreactive palettes are erased from the internal palettes vector. If a preset still references an Effect with AR palette, accessing the palette colors reads from unallocated memory - vector array [] access is not checked for bounds violation.

This is inconsistent to other AR effects, which enable Sound Simulation when the AR usermod is off. Its also inconsistent with the original AR palettes behaviour in WLED-MM, where palette colors come from simulation (fftResult[]) when AR is disabled.

WLED/wled00/colors.cpp

Line 319 in 4efb02d

usermodPalettes.erase(usermodPalettes.begin() + i);

WLED/wled00/json.cpp

Lines 1014 to 1016 in 4efb02d

	} else if (i >= palettesCount) { // usermod palettes (IDs 255, 254, ...)
	int umIdx = i - palettesCount;
	setPaletteColors(curPalette, usermodPalettes[umIdx].palette);

WLED/wled00/FX_fcn.cpp

Lines 276 to 278 in 4efb02d

	default: //progmem palettes
	if (pal > WLED_CUSTOM_PALETTE_ID_BASE) { // usermod palette
	targetPalette = usermodPalettes[WLED_USERMOD_PALETTE_ID_BASE - pal].palette;

[DedeHai]

good catch. The fix for the UM palettes was a bit "last minute" before the 16.0 release to fix custom palettes shifting numbers. My idea was that any usermod can add or remove palettes at any time but clearly I did not think this through.

[softhack007]

I think it was a bug already when AR palettes were moved into the usermod class here in upstream WLED. Not sure if we have a generic problem with custom palettes 🤔, too. If a preset has an effect that needs a removed palette (UM or custom), we should at least use a safe fallback.

[DedeHai]

custom palettes are accessed by ID, I am not 100% sure off the top of my head what happens if that ID does not exist but I don't think it wil caus OOB access.