    static yy_state_type yy_get_previous_state (yyscan_t yyscanner)
{
	yy_state_type yy_current_state;
	char *yy_cp;
    struct yyguts_t * yyg = (struct yyguts_t*)yyscanner;

	yy_current_state = yyg->yy_start;

	for ( yy_cp = yyg->yytext_ptr + YY_MORE_ADJ; yy_cp < yyg->yy_c_buf_p; ++yy_cp )
		{
		YY_CHAR yy_c = (*yy_cp ? yy_ec[YY_SC_TO_UI(*yy_cp)] : 1);
		if ( yy_accept[yy_current_state] )
			{
			yyg->yy_last_accepting_state = yy_current_state;
			yyg->yy_last_accepting_cpos = yy_cp;
			}
		while ( yy_chk[yy_base[yy_current_state] + yy_c] != yy_current_state )
			{
			yy_current_state = (int) yy_def[yy_current_state];
			if ( yy_current_state >= 45 )
				yy_c = yy_meta[(unsigned int) yy_c];
			}
		yy_current_state = yy_nxt[yy_base[yy_current_state] + (unsigned int) yy_c];
		}

	return yy_current_state;
}

The product dereferences a pointer that it expects to be valid but is NULL.