Try this. After few css trick, I managed to fix it myself. This solution override the dialog box height which you mentioned while creating custom action on an object. I hope this will help someone needed. I managed to fix it myself. This solution override the dialog box height which you mentioned while creating custom action on an object. I hope this will help someone needed.
<aura:component implements="force:lightningQuickActionWithoutHeader,force:hasRecordId" controller="MilindTest">
<style>
.cuf-content {
padding: 0 0rem !important;
}
.slds-p-around--medium {
padding: 0rem !important;
}
.slds-modal__content {
overflow-y: hidden !important;
height: unset !important;
max-height: unset !important;
}
</style>
<div class="slds-col modal-header slds-modal__header">
<h2 class="title slds-text-heading--medium">Milind Test</h2>
</div>
<div class="slds-col modal-body scrollable slds-p-around--medium" style="height: 200px; max-height: 400px; overflow-y: auto !important">
<div>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
</div>
</div>
<div class="slds-col modal-footer slds-modal__footer">
<lightning:button variant="neutral" label="Cancel" onclick="{! c.cancelClick }" />
<lightning:button variant="brand" label="Save" onclick="{! c.saveClick }" />
</div>
</aura:component>
