From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33864) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZFlec-00083K-9T for qemu-devel@nongnu.org; Thu, 16 Jul 2015 12:05:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZFleb-00027S-7o for qemu-devel@nongnu.org; Thu, 16 Jul 2015 12:04:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54585) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZFleb-00027G-0f for qemu-devel@nongnu.org; Thu, 16 Jul 2015 12:04:57 -0400 From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Date: Thu, 16 Jul 2015 18:04:00 +0200 Message-Id: <1437062641-12684-3-git-send-email-rkrcmar@redhat.com> In-Reply-To: <1437062641-12684-1-git-send-email-rkrcmar@redhat.com> References: <1437062641-12684-1-git-send-email-rkrcmar@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PATCH v3 2/3] crypto: avoid undefined behavior in nettle calls List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell Calling a function pointer that was cast from an incompatible function results in undefined behavior. 'void *' isn't compatible with 'struct XXX *', so we can't cast to nettle_cipher_func, but have to provide a wrapper. (Conversion from 'void *' to 'struct XXX *' might require computation, which won't be done if we drop argument's true type and pointers can have different sizes so passing arguments on stack would bug.) Having two different prototypes based on nettle version doesn't make this solution any nicer. Reported-by: Peter Maydell Signed-off-by: Radim Kr=C4=8Dm=C3=A1=C5=99 --- v3: make wrappers 'static' v2: new [Peter] crypto/cipher-nettle.c | 43 +++++++++++++++++++++++++++++++++++++++---- 1 file changed, 39 insertions(+), 4 deletions(-) diff --git a/crypto/cipher-nettle.c b/crypto/cipher-nettle.c index e61aaa29f049..3e3c4c9cbf2f 100644 --- a/crypto/cipher-nettle.c +++ b/crypto/cipher-nettle.c @@ -25,8 +25,43 @@ =20 #if CONFIG_NETTLE_VERSION_MAJOR < 3 typedef nettle_crypt_func nettle_cipher_func; + +typedef void * cipher_ctx_t; +typedef unsigned cipher_length_t; +#else +typedef const void * cipher_ctx_t; +typedef size_t cipher_length_t; #endif =20 +static nettle_cipher_func aes_encrypt_wrapper; +static nettle_cipher_func aes_decrypt_wrapper; +static nettle_cipher_func des_encrypt_wrapper; +static nettle_cipher_func des_decrypt_wrapper; + +static void aes_encrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length= , + uint8_t *dst, const uint8_t *src) +{ + aes_encrypt(ctx, length, dst, src); +} + +static void aes_decrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length= , + uint8_t *dst, const uint8_t *src) +{ + aes_encrypt(ctx, length, dst, src); +} + +static void des_encrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length= , + uint8_t *dst, const uint8_t *src) +{ + des_encrypt(ctx, length, dst, src); +} + +static void des_decrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length= , + uint8_t *dst, const uint8_t *src) +{ + des_decrypt(ctx, length, dst, src); +} + typedef struct QCryptoCipherNettle QCryptoCipherNettle; struct QCryptoCipherNettle { void *ctx_encrypt; @@ -87,8 +122,8 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorit= hm alg, des_set_key(ctx->ctx_encrypt, rfbkey); g_free(rfbkey); =20 - ctx->alg_encrypt =3D (nettle_cipher_func *)des_encrypt; - ctx->alg_decrypt =3D (nettle_cipher_func *)des_decrypt; + ctx->alg_encrypt =3D des_encrypt_wrapper; + ctx->alg_decrypt =3D des_decrypt_wrapper; =20 ctx->niv =3D DES_BLOCK_SIZE; break; @@ -102,8 +137,8 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgori= thm alg, aes_set_encrypt_key(ctx->ctx_encrypt, nkey, key); aes_set_decrypt_key(ctx->ctx_decrypt, nkey, key); =20 - ctx->alg_encrypt =3D (nettle_cipher_func *)aes_encrypt; - ctx->alg_decrypt =3D (nettle_cipher_func *)aes_decrypt; + ctx->alg_encrypt =3D aes_encrypt_wrapper; + ctx->alg_decrypt =3D aes_decrypt_wrapper; =20 ctx->niv =3D AES_BLOCK_SIZE; break; --=20 2.4.5