🐛 Add bounding box dimension limit to prevent export DoS

Add max-export-dimension constant (100000 units) and validate in
calculate-dimensions. Reject exports when bounding box width, height,
or position exceeds the limit to prevent resource exhaustion in the
Chromium export pool.

AI-assisted-by: mimo-v2.5-pro

frontend/src/app/main/render.cljs

@@ -15,6 +15,7 @@
    ["react-dom/server" :as rds]
    [app.common.data :as d]
    [app.common.data.macros :as dm]
+   [app.common.exceptions :as ex]
    [app.common.files.helpers :as cfh]
    [app.common.geom.point :as gpt]
    [app.common.geom.rect :as grc]
@@ -59,6 +60,7 @@
    [rumext.v2 :as mf]))
 
 (def ^:const viewbox-decimal-precision 3)
+(def ^:const max-export-dimension 100000)
 (def ^:private default-color clr/canvas)
 
 (mf/defc background
@@ -82,12 +84,20 @@
       (let [bounds
             (->> root-objects
                  (map (partial gsb/get-object-bounds objects))
-                 (grc/join-rects))]
+                 (grc/join-rects))
+            bounds (-> bounds
+                       (update :x mth/finite 0)
+                       (update :y mth/finite 0)
+                       (update :width mth/finite 100000)
+                       (update :height mth/finite 100000))]
+        (when (or (> (:width bounds) max-export-dimension)
+                  (> (:height bounds) max-export-dimension)
+                  (> (+ (:x bounds) (:width bounds)) max-export-dimension)
+                  (> (+ (:y bounds) (:height bounds)) max-export-dimension))
+          (ex/raise :type :validation
+                    :code :export-area-too-large
+                    :hint "export area exceeds maximum allowed dimensions"))
         (-> bounds
-            (update :x mth/finite 0)
-            (update :y mth/finite 0)
-            (update :width mth/finite 100000)
-            (update :height mth/finite 100000)
             (grc/update-rect :position)
             (grc/fix-aspect-ratio aspect-ratio))))))
 

frontend/test/frontend_tests/render_dimensions_test.cljs

@@ -0,0 +1,78 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) KALEIDOS INC Sucursal en España SL
+
+(ns frontend-tests.render-dimensions-test
+  (:require
+   [app.common.geom.rect :as grc]
+   [app.common.geom.shapes.bounds :as gsb]
+   [app.common.test-helpers.files :as cthf]
+   [app.common.test-helpers.ids-map :as cthi]
+   [app.common.test-helpers.shapes :as cths]
+   [app.common.types.shape :as cts]
+   [app.common.uuid :as uuid]
+   [app.main.render :as render]
+   [cljs.test :as t :include-macros true]))
+
+(defn- make-objects
+  "Create a proper objects map with a root frame and the given shapes."
+  [& shapes]
+  (let [root-frame (cts/setup-shape {:id uuid/zero
+                                     :type :frame
+                                     :parent-id uuid/zero
+                                     :frame-id uuid/zero
+                                     :name "Root Frame"
+                                     :shapes (mapv :id shapes)})
+        objects {uuid/zero root-frame}]
+    (reduce (fn [objs shape]
+              (assoc objs (:id shape) (assoc shape :frame-id uuid/zero)))
+            objects
+            shapes)))
+
+(t/deftest calculate-dimensions-normal-bounds
+  (t/testing "Normal bounding box should pass"
+    (let [shape1 (cts/setup-shape {:type :rect :x 100 :y 100 :width 200 :height 150})
+          shape2 (cts/setup-shape {:type :rect :x 400 :y 300 :width 100 :height 100})
+          objects (make-objects shape1 shape2)
+          result (render/calculate-dimensions objects nil)]
+      (t/is (some? result))
+      (t/is (<= (:width result) render/max-export-dimension))
+      (t/is (<= (:height result) render/max-export-dimension)))))
+
+(t/deftest calculate-dimensions-extreme-width
+  (t/testing "Extreme width should throw export-area-too-large"
+    (let [shape (cts/setup-shape {:type :rect :x 0 :y 0 :width 200000 :height 100})
+          objects (make-objects shape)]
+      (t/is (thrown-with-msg?
+             js/Error
+             #"export area exceeds maximum allowed dimensions"
+             (render/calculate-dimensions objects nil))))))
+
+(t/deftest calculate-dimensions-extreme-height
+  (t/testing "Extreme height should throw export-area-too-large"
+    (let [shape (cts/setup-shape {:type :rect :x 0 :y 0 :width 100 :height 200000})
+          objects (make-objects shape)]
+      (t/is (thrown-with-msg?
+             js/Error
+             #"export area exceeds maximum allowed dimensions"
+             (render/calculate-dimensions objects nil))))))
+
+(t/deftest calculate-dimensions-extreme-position
+  (t/testing "Shape at extreme position should throw export-area-too-large"
+    (let [shape (cts/setup-shape {:type :rect :x 500000 :y 500000 :width 100 :height 100})
+          objects (make-objects shape)]
+      (t/is (thrown-with-msg?
+             js/Error
+             #"export area exceeds maximum allowed dimensions"
+             (render/calculate-dimensions objects nil))))))
+
+(t/deftest calculate-dimensions-exactly-at-limit
+  (t/testing "Bounding box exactly at limit should pass"
+    (let [shape (cts/setup-shape {:type :rect :x 0 :y 0 :width render/max-export-dimension :height render/max-export-dimension})
+          objects (make-objects shape)
+          result (render/calculate-dimensions objects nil)]
+      (t/is (some? result))
+      (t/is (<= (:width result) render/max-export-dimension))
+      (t/is (<= (:height result) render/max-export-dimension)))))

frontend/test/frontend_tests/runner.cljs

@@ -51,6 +51,7 @@
    [frontend-tests.plugins.tokens-test]
    [frontend-tests.plugins.utils-test]
    [frontend-tests.plugins.value-objects-test]
+   [frontend-tests.render-dimensions-test]
    [frontend-tests.render-wasm.process-objects-test]
    [frontend-tests.render-wasm.text-editor-caret-color-test]
    [frontend-tests.svg-fills-test]
@@ -160,6 +161,7 @@
    'frontend-tests.ui.gradient-handlers-test
    'frontend-tests.ui.layout-container-multiple-test
    'frontend-tests.ui.measures-menu-props-test
+   'frontend-tests.render-dimensions-test
    'frontend-tests.text-editor-paste-guard-test
    'frontend-tests.ui.settings-password-schema-test
    'frontend-tests.ui.settings-shortcuts-test