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crypto: fix crash when calling digest after piping · nodejs/node@990feaf · GitHub

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Commit 990feaf

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tniessen
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crypto: fix crash when calling digest after piping
When piping data into an SHA3 hash, EVP_DigestFinal_ex is called in hash._flush, bypassing safeguards in the JavaScript layer. Calling hash.digest causes EVP_DigestFinal_ex to be called again, resulting in a segmentation fault in the SHA3 implementation of OpenSSL. A relatively easy solution is to cache the result of calling EVP_DigestFinal_ex until the Hash object is garbage collected. PR-URL: #28251 Fixes: #28245 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
1 parent 17efd93 commit 990feaf

3 files changed

Lines changed: 26 additions & 9 deletions

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‎src/node_crypto.cc‎

Lines changed: 10 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -4634,16 +4634,20 @@ void Hash::HashDigest(const FunctionCallbackInfo<Value>& args) {
46344634
encoding = ParseEncoding(env->isolate(), args[0], BUFFER);
46354635
}
46364636

4637-
unsigned char md_value[EVP_MAX_MD_SIZE];
4638-
unsigned int md_len;
4639-
4640-
EVP_DigestFinal_ex(hash->mdctx_.get(), md_value, &md_len);
4637+
if (hash->md_len_ == 0) {
4638+
// Some hash algorithms such as SHA3 do not support calling
4639+
// EVP_DigestFinal_ex more than once, however, Hash._flush
4640+
// and Hash.digest can both be used to retrieve the digest,
4641+
// so we need to cache it.
4642+
// See https://github.com/nodejs/node/issues/28245.
4643+
EVP_DigestFinal_ex(hash->mdctx_.get(), hash->md_value_, &hash->md_len_);
4644+
}
46414645

46424646
Local<Value> error;
46434647
MaybeLocal<Value> rc =
46444648
StringBytes::Encode(env->isolate(),
4645-
reinterpret_cast<const char*>(md_value),
4646-
md_len,
4649+
reinterpret_cast<const char*>(hash->md_value_),
4650+
hash->md_len_,
46474651
encoding,
46484652
&error);
46494653
if (rc.IsEmpty()) {

‎src/node_crypto.h‎

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -595,12 +595,19 @@ class Hash : public BaseObject {
595595

596596
Hash(Environment* env, v8::Local<v8::Object> wrap)
597597
: BaseObject(env, wrap),
598-
mdctx_(nullptr) {
598+
mdctx_(nullptr),
599+
md_len_(0) {
599600
MakeWeak();
600601
}
601602

603+
~Hash() override {
604+
OPENSSL_cleanse(md_value_, md_len_);
605+
}
606+
602607
private:
603608
EVPMDPointer mdctx_;
609+
unsigned char md_value_[EVP_MAX_MD_SIZE];
610+
unsigned int md_len_;
604611
};
605612

606613
class SignBase : public BaseObject {

‎test/parallel/test-crypto-hash-stream-pipe.js‎

Lines changed: 8 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -30,11 +30,17 @@ const crypto = require('crypto');
3030

3131
const stream = require('stream');
3232
const s = new stream.PassThrough();
33-
const h = crypto.createHash('sha1');
34-
const expect = '15987e60950cf22655b9323bc1e281f9c4aff47e';
33+
const h = crypto.createHash('sha3-512');
34+
const expect = '36a38a2a35e698974d4e5791a3f05b05' +
35+
'198235381e864f91a0e8cd6a26b677ec' +
36+
'dcde8e2b069bd7355fabd68abd6fc801' +
37+
'19659f25e92f8efc961ee3a7c815c758';
3538

3639
s.pipe(h).on('data', common.mustCall(function(c) {
3740
assert.strictEqual(c, expect);
41+
// Calling digest() after piping into a stream with SHA3 should not cause
42+
// a segmentation fault, see https://github.com/nodejs/node/issues/28245.
43+
assert.strictEqual(h.digest('hex'), expect);
3844
})).setEncoding('hex');
3945

4046
s.end('aoeu');

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