EQEmulator Forums - array index error

In spell_effects.cpp there are a couple of lines that were introduced with the Enchanter rune patch that can be called with a negative array index.
I noticed this call was being made for Necromancers casting their pet spell, but that is likely not the only case this happens.
The pet spell fails the if((CalcBuffDuration(caster,this,spell_id)-1) != 0) and goes to the else assigning buffslot = -2
then the initialization to 0 of the buffs array for melee_rune and magic_rune is where buffslot(-2) is used on the array. This had the effect
of setting Agility and Dexterity to 0 on the server side for the Necromancer, but didn't crash anything.

Code:

bool Mob::SpellEffect(Mob* caster, int16 spell_id, float partial)

{

    _ZP(Mob_SpellEffect);



    int caster_level, buffslot, effect, effect_value, i;

    ItemInst *SummonedItem=NULL;

#ifdef SPELL_EFFECT_SPAM

#define _EDLEN        200

    char effect_desc[_EDLEN];

#endif



    if(!IsValidSpell(spell_id))

        return false;



    const SPDat_Spell_Struct &spell = spells[spell_id];



    if((CalcBuffDuration(caster,this,spell_id)-1) != 0){

        buffslot = AddBuff(caster, spell_id);

        if(buffslot == -1)        // stacking failure

            return false;

    } else {

        buffslot = -2;        //represents not a buff I guess

    }



    caster_level = caster ? caster->GetCasterLevel(spell_id) : GetCasterLevel(spell_id);



#ifdef SPELL_EFFECT_SPAM

        Message(0, "You are affected by spell '%s' (id %d)", spell.name, spell_id);

        if(buffslot >= 0)

        {

            Message(0, "Buff slot:  %d  Duration:  %d tics", buffslot, buffs[buffslot].ticsremaining);

        }

#endif



        buffs[buffslot].melee_rune = 0;

        buffs[buffslot].magic_rune = 0;

I think it's just a simple fix of surrounding these two lines with an if check for safe array indexing

Code:

    if(buffslot >= 0) {

        buffs[buffslot].melee_rune = 0;

        buffs[buffslot].magic_rune = 0;

    }