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

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This commit is contained in:
Jonas Jenwald 2016-09-23 14:10:27 +02:00
parent 6c263c1994
commit 3e77cf6b32
3 changed files with 33 additions and 16 deletions
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15
src/core/crypto.js
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@ -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) {