BIO_dump_fp causing hundreds of valgrind errors - c++

Question

I'm trying to use the OpenSSL library for AES encryption. Everything compiles and seems to work fine. However, when I use BIO_dump_fp(stdout, (char*)ciphertext, ciphertext_len) valgrind ends up reporting hundreds of errors, mostly "conditional jump of move depends on uninitialized value(s)" errors, like this one:
Conditional jump or move depends on uninitialised value(s)
at 0x579A9C3: fwrite (iofwrite.c:49)
by 0x4F187B0: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
by 0x4F18AC4: BIO_dump_indent_cb (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
by 0x401748: main (in /home/van/Desktop/aes-test/temp/test)
Can these errors be safely ignored (i.e. are these false positives)? If it matters, I'm using Ubuntu 14.04, g++ version 4.8.2, valgrind 3.10.
UPDATE: my full source code is as follows:
#include <stdio.h>
#include "QAesHelper.h"
int main(int argc, char *argv[])
{
unsigned char iv[] = "1234567812345678";
unsigned char key[] = "Testing Testing...";
printf("Size of key: %d\n", (int)sizeof(key));
unsigned char plaintext[] = "The quick brown fox jumps over the lazy dog";
int plaintext_len = sizeof(plaintext);
printf("Size of plaintext: %d\n", plaintext_len);
unsigned char *ciphertext = (unsigned char*)malloc(plaintext_len + 32);
unsigned char *decryptedtext = (unsigned char*)malloc(plaintext_len + 2);
QAesHelper *aesHelper = new QAesHelper(key, sizeof(key));
int ciphertext_len = aesHelper->encrypt(plaintext, plaintext_len, iv, sizeof(iv), &ciphertext);
int decryptedtext_len = aesHelper->decrypt(ciphertext, ciphertext_len + 1, iv, sizeof(iv), &decryptedtext);
// If I remove the following line (BIO_dump_fp...), then
// valgrind reports no errors. With this line left in, there
// are over 900 errors reported.
BIO_dump_fp(stdout, (char*)ciphertext, ciphertext_len);
delete aesHelper;
free(ciphertext);
free(decryptedtext);
return 0;
}
And QAesHelper::encrypt() is:
int QAesHelper::encrypt(unsigned char *plaintext, int plaintext_len, unsigned char *iv, int iv_len, unsigned char **ciphertext)
{
EVP_CIPHER_CTX *ctx;
int len;
int ciphertext_len;
if(!(ctx = EVP_CIPHER_CTX_new())) handleErrors();
if(1 != EVP_EncryptInit_ex(ctx, EVP_aes_256_cbc(), NULL, key, iv))
handleErrors();
if(1 != EVP_EncryptUpdate(ctx, *ciphertext, &len, plaintext, plaintext_len))
handleErrors();
ciphertext_len = len;
if(1 != EVP_EncryptFinal_ex(ctx, *ciphertext + len, &len)) handleErrors();
ciphertext_len += len;
EVP_CIPHER_CTX_free(ctx);
return ciphertext_len;
}

Answer 1

Its not an error. OpenSSL heavily uses uninitialized memory segments.
Valgrind treats such usage as error and warns about it. Its normal behaviour which can be beautified in some extent:
write and use valgrind suppression file valgrind --gen-suppressions=no|yes|all
compile openssl with PURIFY macro enabled in cflags
push to valgrind --error-limit=no and ignore warnings from libssl/libcrypto