| Subject: | Memory leak in EC_POINT::point2hex() |
I found that Crypt::OpenSSL::EC::EC_POINT::point2hex() produces memory leak. See this example:
use strict;
use Crypt::OpenSSL::EC;
use Crypt::OpenSSL::Bignum;
my $p = Crypt::OpenSSL::Bignum->new_from_hex( 'ffffffff00000001000000000000000000000000ffffffffffffffffffffffff' );
my $a = Crypt::OpenSSL::Bignum->new_from_hex( 'ffffffff00000001000000000000000000000000fffffffffffffffffffffffc' );
my $b = Crypt::OpenSSL::Bignum->new_from_hex( '5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b' );
my $x = Crypt::OpenSSL::Bignum->new_from_hex( '6b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c296' );
my $y = Crypt::OpenSSL::Bignum->new_from_hex( '4fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5' );
my $n = Crypt::OpenSSL::Bignum->new_from_hex( 'ffffffff00000000ffffffffffffffffbce6faada7179e84f3b9cac2fc632551' );
my $h = Crypt::OpenSSL::Bignum->one;
my $ctx = Crypt::OpenSSL::Bignum::CTX->new();
my $method = Crypt::OpenSSL::EC::EC_GFp_mont_method();
my $group = Crypt::OpenSSL::EC::EC_GROUP::new($method);
$group->set_curve_GFp( $p, $a, $b, $ctx );
my $G = Crypt::OpenSSL::EC::EC_POINT::new($group);
Crypt::OpenSSL::EC::EC_POINT::set_affine_coordinates_GFp( $group, $G, $x, $y, $ctx );
$group->set_generator( $G, $n, $h );
die 'bad curve' unless Crypt::OpenSSL::EC::EC_GROUP::check( $group, $ctx );
warn "Starting: $$";
for (1..10_000_000) {
my $p = Crypt::OpenSSL::EC::EC_POINT::new($group);
my $r = Crypt::OpenSSL::EC::EC_POINT::point2hex($group, $p, POINT_CONVERSION_UNCOMPRESSED, $ctx);
#my $r = Crypt::OpenSSL::EC::EC_POINT::point2oct($group, $p, POINT_CONVERSION_UNCOMPRESSED, $ctx);
}
warn "See my memory usage";
<>;
Memory usage of this process grows without a stop until 10_000_000 iterations will be processed. At the end process eats about 300 mb of memory.
If we'll use point2oct() instead, memory usage remains constant and is about 6 mb. I think the reason can be found at https://www.openssl.org/docs/man1.1.0/crypto/EC_POINT_point2hex.html:
The function EC_POINT_point2hex() will allocate sufficient memory to store the hexadecimal string. It is the caller's responsibility to free this memory with a subsequent call to OPENSSL_free(). Other functions which returns char* may has same bug.