Before you close your application down try calling: CRYPTO_cleanup_all_ex_data() See: https://wiki.openssl.org/index.php/Library_Initialization#Cleanup The whole dance around init/de-init of the library becomes a whole lot easier in 1.1.0 (it should all happen automatically) - but in 1.0.2 you have to call several functions to properly de-initialise the library. Matt On 22/11/17 10:19, Seiberlich, Holger via openssl-users wrote: > Dear OpenSSL community, > > in a C++ (vc14, OpenSSL 1.0.2h/m) project, I'm trying to negotiate a secret between two parties, using EC crypto. I've used > https://wiki.openssl.org/index.php/EVP_Key_Agreement > as a recipe and wrapped memory allocations into unique_ptrs. The code fulfills its purpose of deriving a shared secret, but memory leak detection with > _CrtSetDbgFlag( _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF ); > _CrtSetReportMode( _CRT_WARN, _CRTDBG_MODE_FILE ); > _CrtSetReportFile( _CRT_WARN, _CRTDBG_FILE_STDOUT ); > produces a warning: > Detected memory leaks! > Dumping objects -> > {10316} normal block at 0x00307680, 12 bytes long. > Data: < v0 > F0 76 30 00 00 00 00 00 0D 00 00 00 > {10315} normal block at 0x00351068, 16 bytes long. > Data: < > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > {10314} normal block at 0x00350F68, 20 bytes long. > Data: < h 5 > 00 00 00 00 68 10 35 00 00 00 00 00 04 00 00 00 > {10313} normal block at 0x003076F0, 12 bytes long. > Data: < h 5 > 0D 00 00 00 68 0F 35 00 00 00 00 00 > {10312} normal block at 0x00310A70, 64 bytes long. > Data: < > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > {10311} normal block at 0x00309E98, 96 bytes long. > Data: <p 1 A ' > 70 0A 31 00 90 41 20 0F A0 0D 27 0F 08 00 00 00 > Object dump complete. > > Let me note two things: > - The line without which the memory leak disappears is the line triggering the actual secret derivation: > if(EVP_PKEY_derive(ctx.get(), skey.get(), &skeylen) <= 0) > - The size of the leak is independent of how often I run the procedure of generating two sets of keys and then calling DeriveSecret(). > > *** > Therefore, I'm wondering whether I've missed a call to free that I must trigger to deallocate this memory. > *** > > I have added an allocation hook to check, as an example, when the 96-byte allocation occurs: > > [Name] [Language] > libeay32.dll!default_malloc_ex(unsigned int num, const char * file, int line) Line 79 C > libeay32.dll!CRYPTO_malloc(int num, const char * file, int line) Line 342 C > libeay32.dll!lh_new(unsigned long(*)(const void *) h, int(*)(const void *, const void *) c) Line 120 C > libeay32.dll!ex_data_check() Line 279 C > libeay32.dll!def_get_class(int class_index) Line 316 C > libeay32.dll!int_new_ex_data(int class_index, void * obj, crypto_ex_data_st * ad) Line 421 C > libeay32.dll!CRYPTO_new_ex_data(int class_index, void * obj, crypto_ex_data_st * ad) Line 583 C > libeay32.dll!ECDH_DATA_new_method(engine_st * engine) Line 165 C > libeay32.dll!ecdh_data_new() Line 178 C > libeay32.dll!ecdh_check(ec_key_st * key) Line 215 C > libeay32.dll!ECDH_compute_key(void * out, unsigned int outlen, const ec_point_st * pub_key, ec_key_st * eckey, void *(*)(const void *, unsigned int, void *, unsigned int *) KDF) Line 77 C > libeay32.dll!pkey_ec_derive(evp_pkey_ctx_st * ctx, unsigned char * key, unsigned int * keylen) Line 237 C > libeay32.dll!pkey_ec_kdf_derive(evp_pkey_ctx_st * ctx, unsigned char * key, unsigned int * keylen) Line 252 C > libeay32.dll!EVP_PKEY_derive(evp_pkey_ctx_st * ctx, unsigned char * key, unsigned int * pkeylen) Line 345 C > [.]DeriveSecret() Line 802 C++ > > Please see below for how I call EVP_PKEY_derive. Can you tell me what I'm missing? Do you need more info? > > Thank you for looking into this and helping! > > Regards, > Holger > > > template<typename T> using deleted_unique_ptr = std::unique_ptr<T,std::function<void(T*)>>; > > deleted_unique_ptr<EVP_PKEY> m_pOwnKey; > deleted_unique_ptr<EVP_PKEY> m_pPeerKey; > > void [...]::DeriveSecret() > { > if (!(m_pOwnKey && m_pOwnKey->pkey.ec)) > { > throw KeyUninitializedError("Secret cannot be derived if own key is missing"); > } > if (!m_pPeerKey) > { > throw KeyUninitializedError("Secret cannot be derived if peer key is missing"); > } > > deleted_unique_ptr<EVP_PKEY_CTX> ctx(EVP_PKEY_CTX_new(m_pOwnKey.get(), NULL), [](EVP_PKEY_CTX* obj) > { > EVP_PKEY_CTX_free(obj); > }); > > size_t skeylen; > if(!ctx) > { > /* Error occurred */ > throw OpenSslError("Error creating EVP_PKEY_CTX"); > } > if(EVP_PKEY_derive_init(ctx.get()) <= 0) > { > /* Error */ > throw OpenSslError("Error in EVP_PKEY_derive_init"); > } > if(EVP_PKEY_derive_set_peer(ctx.get(), m_pPeerKey.get()) <= 0) > { > /* Error */ > throw OpenSslError("Error setting peer key in key negotiation"); > } > /* Determine buffer length */ > if(EVP_PKEY_derive(ctx.get(), NULL, &skeylen) <= 0) > { > /* Error */ > throw OpenSslError("Error computing length of shared secret"); > } > > if (skeylen != secretSize) > { > throw OpenSslError("Shared secret has unexpected size"); > } > > deleted_unique_ptr<unsigned char> skey((unsigned char*)OPENSSL_malloc(skeylen), [](unsigned char* obj) > { > OPENSSL_free(obj); > }); > > /// @note The derivation of the secret seems to leak memory within OpenSSL > if(EVP_PKEY_derive(ctx.get(), skey.get(), &skeylen) <= 0) > { > /* Error */ > throw OpenSslError("Error deriving shared secret"); > } > > [...] > } > > > > > Dr. Holger Seiberlich > Software Developer > Bruker Optik GmbH > Rudolf-Plank-Str. 27 > 76275 Ettlingen, Germany > > Phone: +49 7243 504-2626 > Fax: +49 7243 504-42626 > Holger.Seiberlich@xxxxxxxxxx > www.bruker.com > > Sitz der Gesellschaft ist Ettlingen, HRB 36 2608 Amtsgericht Mannheim > Geschäftsführer: Urban Faeh, Marc Beisel, Juergen Srega > > Diese E-Mail und alle Anlagen können Betriebs- oder Geschäftsgeheimnisse, oder sonstige vertrauliche Informationen enthalten. 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