Prevent an infinite loop in XRef_fetchUncompressed for encrypted PDF files with indirect objects in the /Encrypt dictionary (issue 7665)

src/core/crypto.js

@@ -31,11 +31,12 @@
 var PasswordException = sharedUtil.PasswordException;
 var PasswordResponses = sharedUtil.PasswordResponses;
 var bytesToString = sharedUtil.bytesToString;
+var warn = sharedUtil.warn;
 var error = sharedUtil.error;
+var assert = sharedUtil.assert;
 var isInt = sharedUtil.isInt;
 var stringToBytes = sharedUtil.stringToBytes;
 var utf8StringToString = sharedUtil.utf8StringToString;
-var warn = sharedUtil.warn;
 var Name = corePrimitives.Name;
 var isName = corePrimitives.isName;
 var isDict = corePrimitives.isDict;
@@ -1932,6 +1933,7 @@ var CipherTransformFactory = (function CipherTransformFactoryClosure() {
         var cfDict = dict.get('CF');
         var streamCryptoName = dict.get('StmF');
         if (isDict(cfDict) && isName(streamCryptoName)) {
+          cfDict.suppressEncryption = true; // See comment below.
           var handlerDict = cfDict.get(streamCryptoName.name);
           keyLength = (handlerDict && handlerDict.get('Length')) || 128;
           if (keyLength < 40) {
@@ -2013,7 +2015,15 @@ var CipherTransformFactory = (function CipherTransformFactoryClosure() {
     this.encryptionKey = encryptionKey;
 
     if (algorithm >= 4) {
-      this.cf = dict.get('CF');
+      var cf = dict.get('CF');
+      if (isDict(cf)) {
+        // The 'CF' dictionary itself should not be encrypted, and by setting
+        // `suppressEncryption` we can prevent an infinite loop inside of
+        // `XRef_fetchUncompressed` if the dictionary contains indirect objects
+        // (fixes issue7665.pdf).
+        cf.suppressEncryption = true;
+      }
+      this.cf = cf;
       this.stmf = dict.get('StmF') || identityName;
       this.strf = dict.get('StrF') || identityName;
       this.eff = dict.get('EFF') || this.stmf;
@@ -2041,6 +2051,7 @@ var CipherTransformFactory = (function CipherTransformFactoryClosure() {
   }
 
   function buildCipherConstructor(cf, name, num, gen, key) {
+    assert(isName(name), 'Invalid crypt filter name.');
     var cryptFilter = cf.get(name.name);
     var cfm;
     if (cryptFilter !== null && cryptFilter !== undefined) {

src/core/obj.js

@@ -633,6 +633,11 @@ var XRef = (function XRefClosure() {
       if (encrypt) {
         var ids = trailerDict.get('ID');
         var fileId = (ids && ids.length) ? ids[0] : '';
+        // The 'Encrypt' dictionary itself should not be encrypted, and by
+        // setting `suppressEncryption` we can prevent an infinite loop inside
+        // of `XRef_fetchUncompressed` if the dictionary contains indirect
+        // objects (fixes issue7665.pdf).
+        encrypt.suppressEncryption = true;
         this.encrypt = new CipherTransformFactory(encrypt, fileId,
                                                   this.password);
       }
@@ -1079,11 +1084,11 @@ var XRef = (function XRefClosure() {
       return null;
     },
 
-    fetchIfRef: function XRef_fetchIfRef(obj) {
+    fetchIfRef: function XRef_fetchIfRef(obj, suppressEncryption) {
       if (!isRef(obj)) {
         return obj;
       }
-      return this.fetch(obj);
+      return this.fetch(obj, suppressEncryption);
     },
 
     fetch: function XRef_fetch(ref, suppressEncryption) {
@@ -1201,11 +1206,11 @@ var XRef = (function XRefClosure() {
       return xrefEntry;
     },
 
-    fetchIfRefAsync: function XRef_fetchIfRefAsync(obj) {
+    fetchIfRefAsync: function XRef_fetchIfRefAsync(obj, suppressEncryption) {
       if (!isRef(obj)) {
         return Promise.resolve(obj);
       }
-      return this.fetchAsync(obj);
+      return this.fetchAsync(obj, suppressEncryption);
     },
 
     fetchAsync: function XRef_fetchAsync(ref, suppressEncryption) {

src/core/primitives.js

@@ -73,6 +73,7 @@ var Dict = (function DictClosure() {
     this.map = Object.create(null);
     this.xref = xref;
     this.objId = null;
+    this.suppressEncryption = false;
     this.__nonSerializable__ = nonSerializable; // disable cloning of the Dict
   }
 
@@ -84,40 +85,40 @@ var Dict = (function DictClosure() {
     // automatically dereferences Ref objects
     get: function Dict_get(key1, key2, key3) {
       var value;
-      var xref = this.xref;
+      var xref = this.xref, suppressEncryption = this.suppressEncryption;
       if (typeof (value = this.map[key1]) !== 'undefined' || key1 in this.map ||
           typeof key2 === 'undefined') {
-        return xref ? xref.fetchIfRef(value) : value;
+        return xref ? xref.fetchIfRef(value, suppressEncryption) : value;
       }
       if (typeof (value = this.map[key2]) !== 'undefined' || key2 in this.map ||
           typeof key3 === 'undefined') {
-        return xref ? xref.fetchIfRef(value) : value;
+        return xref ? xref.fetchIfRef(value, suppressEncryption) : value;
       }
       value = this.map[key3] || null;
-      return xref ? xref.fetchIfRef(value) : value;
+      return xref ? xref.fetchIfRef(value, suppressEncryption) : value;
     },
 
     // Same as get(), but returns a promise and uses fetchIfRefAsync().
     getAsync: function Dict_getAsync(key1, key2, key3) {
       var value;
-      var xref = this.xref;
+      var xref = this.xref, suppressEncryption = this.suppressEncryption;
       if (typeof (value = this.map[key1]) !== 'undefined' || key1 in this.map ||
           typeof key2 === 'undefined') {
         if (xref) {
-          return xref.fetchIfRefAsync(value);
+          return xref.fetchIfRefAsync(value, suppressEncryption);
         }
         return Promise.resolve(value);
       }
       if (typeof (value = this.map[key2]) !== 'undefined' || key2 in this.map ||
           typeof key3 === 'undefined') {
         if (xref) {
-          return xref.fetchIfRefAsync(value);
+          return xref.fetchIfRefAsync(value, suppressEncryption);
         }
         return Promise.resolve(value);
       }
       value = this.map[key3] || null;
       if (xref) {
-        return xref.fetchIfRefAsync(value);
+        return xref.fetchIfRefAsync(value, suppressEncryption);
       }
       return Promise.resolve(value);
     },
@@ -125,7 +126,7 @@ var Dict = (function DictClosure() {
     // Same as get(), but dereferences all elements if the result is an Array.
     getArray: function Dict_getArray(key1, key2, key3) {
       var value = this.get(key1, key2, key3);
-      var xref = this.xref;
+      var xref = this.xref, suppressEncryption = this.suppressEncryption;
       if (!isArray(value) || !xref) {
         return value;
       }
@@ -134,7 +135,7 @@ var Dict = (function DictClosure() {
         if (!isRef(value[i])) {
           continue;
         }
-        value[i] = xref.fetch(value[i]);
+        value[i] = xref.fetch(value[i], suppressEncryption);
       }
       return value;
     },