Validate additional font-dictionary properties

Author: Snuffleupagus

src/core/core_utils.js

@@ -218,6 +218,21 @@ function isWhiteSpace(ch) {
   return ch === 0x20 || ch === 0x09 || ch === 0x0d || ch === 0x0a;
 }
 
+/**
+ * Checks if something is an Array containing only numbers,
+ * and (optionally) checks its length.
+ * @param {any} arr
+ * @param {number | null} len
+ * @returns {boolean}
+ */
+function isNumberArray(arr, len) {
+  return (
+    Array.isArray(arr) &&
+    (len === null || arr.length === len) &&
+    arr.every(x => typeof x === "number")
+  );
+}
+
 /**
  * AcroForm field names use an array like notation to refer to
  * repeated XFA elements e.g. foo.bar[nnn].
@@ -637,6 +652,7 @@ export {
   getRotationMatrix,
   getSizeInBytes,
   isAscii,
+  isNumberArray,
   isWhiteSpace,
   log2,
   MissingDataException,

src/core/evaluator.js

@@ -73,6 +73,7 @@ import { getGlyphsUnicode } from "./glyphlist.js";
 import { getMetrics } from "./metrics.js";
 import { getUnicodeForGlyph } from "./unicode.js";
 import { ImageResizer } from "./image_resizer.js";
+import { isNumberArray } from "./core_utils.js";
 import { MurmurHash3_64 } from "../shared/murmurhash3.js";
 import { OperatorList } from "./operator_list.js";
 import { PDFImage } from "./image.js";
@@ -4077,8 +4078,14 @@ class PartialEvaluator {
       composite = true;
     }
 
-    const firstChar = dict.get("FirstChar") || 0,
-      lastChar = dict.get("LastChar") || (composite ? 0xffff : 0xff);
+    let firstChar = dict.get("FirstChar");
+    if (!Number.isInteger(firstChar)) {
+      firstChar = 0;
+    }
+    let lastChar = dict.get("LastChar");
+    if (!Number.isInteger(lastChar)) {
+      lastChar = composite ? 0xffff : 0xff;
+    }
     const descriptor = dict.get("FontDescriptor");
     const toUnicode = dict.get("ToUnicode") || baseDict.get("ToUnicode");
 
@@ -4206,11 +4213,15 @@ class PartialEvaluator {
 
     if (!descriptor) {
       if (isType3Font) {
+        let bbox = dict.getArray("FontBBox");
+        if (!isNumberArray(bbox, 4)) {
+          bbox = [0, 0, 0, 0];
+        }
         // FontDescriptor is only required for Type3 fonts when the document
         // is a tagged pdf. Create a barbebones one to get by.
         descriptor = new Dict(null);
         descriptor.set("FontName", Name.get(type));
-        descriptor.set("FontBBox", dict.getArray("FontBBox") || [0, 0, 0, 0]);
+        descriptor.set("FontBBox", bbox);
       } else {
         // Before PDF 1.5 if the font was one of the base 14 fonts, having a
         // FontDescriptor was not required.
@@ -4392,13 +4403,37 @@ class PartialEvaluator {
     }
 
     let fontMatrix = dict.getArray("FontMatrix");
-    if (
-      !Array.isArray(fontMatrix) ||
-      fontMatrix.length !== 6 ||
-      fontMatrix.some(x => typeof x !== "number")
-    ) {
+    if (!isNumberArray(fontMatrix, 6)) {
       fontMatrix = FONT_IDENTITY_MATRIX;
     }
+    let bbox = descriptor.getArray("FontBBox") || dict.getArray("FontBBox");
+    if (!isNumberArray(bbox, 4)) {
+      bbox = undefined;
+    }
+    let ascent = descriptor.get("Ascent");
+    if (typeof ascent !== "number") {
+      ascent = undefined;
+    }
+    let descent = descriptor.get("Descent");
+    if (typeof descent !== "number") {
+      descent = undefined;
+    }
+    let xHeight = descriptor.get("XHeight");
+    if (typeof xHeight !== "number") {
+      xHeight = 0;
+    }
+    let capHeight = descriptor.get("CapHeight");
+    if (typeof capHeight !== "number") {
+      capHeight = 0;
+    }
+    let flags = descriptor.get("Flags");
+    if (!Number.isInteger(flags)) {
+      flags = 0;
+    }
+    let italicAngle = descriptor.get("ItalicAngle");
+    if (typeof italicAngle !== "number") {
+      italicAngle = 0;
+    }
 
     const properties = {
       type,
@@ -4416,13 +4451,13 @@ class PartialEvaluator {
       firstChar,
       lastChar,
       toUnicode,
-      bbox: descriptor.getArray("FontBBox") || dict.getArray("FontBBox"),
-      ascent: descriptor.get("Ascent"),
-      descent: descriptor.get("Descent"),
-      xHeight: descriptor.get("XHeight") || 0,
-      capHeight: descriptor.get("CapHeight") || 0,
-      flags: descriptor.get("Flags"),
-      italicAngle: descriptor.get("ItalicAngle") || 0,
+      bbox,
+      ascent,
+      descent,
+      xHeight,
+      capHeight,
+      flags,
+      italicAngle,
       isType3Font,
       cssFontInfo,
       scaleFactors: glyphScaleFactors,

src/core/font_renderer.js

@@ -23,6 +23,7 @@ import {
 } from "../shared/util.js";
 import { CFFParser } from "./cff_parser.js";
 import { getGlyphsUnicode } from "./glyphlist.js";
+import { isNumberArray } from "./core_utils.js";
 import { StandardEncoding } from "./encodings.js";
 import { Stream } from "./stream.js";
 
@@ -750,7 +751,7 @@ class Commands {
 
   add(cmd, args) {
     if (args) {
-      if (args.some(arg => typeof arg !== "number")) {
+      if (!isNumberArray(args, null)) {
         warn(
           `Commands.add - "${cmd}" has at least one non-number arg: "${args}".`
         );

src/core/function.js

@@ -23,6 +23,7 @@ import {
 } from "../shared/util.js";
 import { PostScriptLexer, PostScriptParser } from "./ps_parser.js";
 import { BaseStream } from "./base_stream.js";
+import { isNumberArray } from "./core_utils.js";
 import { LocalFunctionCache } from "./image_utils.js";
 
 class PDFFunctionFactory {
@@ -117,16 +118,9 @@ function toNumberArray(arr) {
   if (!Array.isArray(arr)) {
     return null;
   }
-  const length = arr.length;
-  for (let i = 0; i < length; i++) {
-    if (typeof arr[i] !== "number") {
-      // Non-number is found -- convert all items to numbers.
-      const result = new Array(length);
-      for (let j = 0; j < length; j++) {
-        result[j] = +arr[j];
-      }
-      return result;
-    }
+  if (!isNumberArray(arr, null)) {
+    // Non-number is found -- convert all items to numbers.
+    return arr.map(x => +x);
   }
   return arr;
 }