Reject deriveBits() for PBKDF2 when given a length of 0.

components/webcrypto/algorithms/pbkdf2.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdint.h>
 
 #include "base/memory/ptr_util.h"
 #include "base/stl_util.h"
 #include "components/webcrypto/algorithm_implementation.h"
 #include "components/webcrypto/algorithms/secret_key_util.h"
@@ skipping 46 matching lines @@
                     unsigned int optional_length_bits,
                     std::vector<uint8_t>* derived_bytes) const override {
     crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
 
     if (!has_optional_length_bits)
       return Status::ErrorPbkdf2DeriveBitsLengthNotSpecified();
 
     if (optional_length_bits % 8)
       return Status::ErrorPbkdf2InvalidLength();
 
+    // According to RFC 2898 "dkLength" (derived key length) is
+    // described as being a "positive integer", so it is an error for
+    // it to be 0.
+    if (optional_length_bits == 0)
+      return Status::ErrorPbkdf2DeriveBitsLengthZero();
+
     const blink::WebCryptoPbkdf2Params* params = algorithm.pbkdf2Params();
 
     if (params->iterations() == 0)
       return Status::ErrorPbkdf2Iterations0();
 
     const EVP_MD* digest_algorithm = GetDigest(params->hash());
     if (!digest_algorithm)
       return Status::ErrorUnsupported();
 
     unsigned int keylen_bytes = optional_length_bits / 8;
@@ skipping 28 matching lines @@
   }
 };
 
 }  // namespace
 
 std::unique_ptr<AlgorithmImplementation> CreatePbkdf2Implementation() {
   return base::WrapUnique(new Pbkdf2Implementation);
 }
 
 }  // namespace webcrypto