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authorRadim Krčmář <rkrcmar@redhat.com>2015-07-10 19:18:01 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2015-07-16 20:00:21 +0200
commitd3462e378f40ba6838b6c42584c30769ca633e6f (patch)
tree6c07f65460414fb2c9343fe6eb3ac4ed8bc66256
parentbecaeb726ae7da4212a788773ebdfe87b4833f5c (diff)
downloadqemu-arm-d3462e378f40ba6838b6c42584c30769ca633e6f.tar.gz
crypto: avoid undefined behavior in nettle calls
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 <peter.maydell@linaro.org> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Message-Id: <1437062641-12684-3-git-send-email-rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--crypto/cipher-nettle.c43
1 files changed, 39 insertions, 4 deletions
diff --git a/crypto/cipher-nettle.c b/crypto/cipher-nettle.c
index e61aaa29f0..a55a8e8bc5 100644
--- a/crypto/cipher-nettle.c
+++ b/crypto/cipher-nettle.c
@@ -25,8 +25,43 @@
#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
+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(QCryptoCipherAlgorithm alg,
des_set_key(ctx->ctx_encrypt, rfbkey);
g_free(rfbkey);
- ctx->alg_encrypt = (nettle_cipher_func *)des_encrypt;
- ctx->alg_decrypt = (nettle_cipher_func *)des_decrypt;
+ ctx->alg_encrypt = des_encrypt_wrapper;
+ ctx->alg_decrypt = des_decrypt_wrapper;
ctx->niv = DES_BLOCK_SIZE;
break;
@@ -102,8 +137,8 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
aes_set_encrypt_key(ctx->ctx_encrypt, nkey, key);
aes_set_decrypt_key(ctx->ctx_decrypt, nkey, key);
- ctx->alg_encrypt = (nettle_cipher_func *)aes_encrypt;
- ctx->alg_decrypt = (nettle_cipher_func *)aes_decrypt;
+ ctx->alg_encrypt = aes_encrypt_wrapper;
+ ctx->alg_decrypt = aes_decrypt_wrapper;
ctx->niv = AES_BLOCK_SIZE;
break;