CustomMaterial crashes engine

When using a CustomMaterial, the flow of rendering calls is as follows:

RenderInteriorMgr::render()
--- MatInstance::setupPass( ) (1)
--- MatInstance::getCurPass() (2)
--- MatInstance::setTextureStages() (3)
Crash

When MatInstance::setupPass( ) is called in step 1 for a custom material, the call is delegated to CustomMaterial::setupPass and the member mCurPass of MatInstance is NOT incremented and stays at it's default value 0.

When MatInstance::getCurPass( ) is called in step 2 the inline function

U32 getCurPass(){ return mCurPass - 1; }

is executed with a value of 0 for mCurPass resulting in a return value of -1 that is casted to an U32 resulting in a signed value of 4294967295


When MatInstance::setTextureStages( ) is called in step 3 the input param pass is filled with 4294967295 and is used to index the mPasses array.
This access results in an access violation and crashes the application.

I fixed the problem by changing the inline function to

S32 getCurPass(){ return mCurPass - 1; }

With the signed value the material checks for mCurrPass > 0 are working again and preventing some out of bounds accesses.
However, I am not quite sure, if this is sufficient in all places, since MatInstance::setupPass( ) bails out for a CustomMaterial without doing some initializations that are done for normal materials.

Maybe someone form GG can have a look at this.

-- Markus