Fix NULL pointer crash in OQS KEM encaps/decaps error handling (#184)

* Fix NULL pointer crash in OQS KEM encaps/decaps error handling

Signed-off-by: Andrew Younkers <[email protected]>

* initialize r at top of functions

Signed-off-by: Andrew Younkers <[email protected]>

---------

Signed-off-by: Andrew Younkers <[email protected]>

Author: andrewyounkers

kexoqs.c

@@ -42,7 +42,7 @@ static int kex_kem_generic_keypair(OQS_KEM *kem, struct kex *kex)
 {
   struct sshbuf *buf = NULL;
   u_char *cp = NULL;
-  int r;
+  int r = SSH_ERR_INTERNAL_ERROR;
   if ((buf = sshbuf_new()) == NULL) {
     return SSH_ERR_ALLOC_FAIL;
   }
@@ -71,7 +71,7 @@ static int kex_kem_generic_enc(OQS_KEM *kem, struct kex *kex,
   struct sshbuf *buf = NULL;
   const u_char *client_pub;
   u_char *kem_key = NULL, *ciphertext;
-  int r;
+  int r = SSH_ERR_INTERNAL_ERROR;
   *server_blobp = NULL;
   *shared_secretp = NULL;
   if (sshbuf_len(client_blob) != kem->length_public_key) {
@@ -125,7 +125,7 @@ static int kex_kem_generic_dec(OQS_KEM *kem,
   struct sshbuf *buf = NULL;
   u_char *kem_key = NULL;
   const u_char *ciphertext;
-  int r;
+  int r = SSH_ERR_INTERNAL_ERROR;
   *shared_secretp = NULL;
   if (sshbuf_len(server_blob) != kem->length_ciphertext) {
     r = SSH_ERR_SIGNATURE_INVALID;

kexoqsecdh.c

@@ -184,7 +184,7 @@ static int kex_kem_generic_with_ec_enc(OQS_KEM *kem,
   struct sshbuf *ecdh_server_blob = NULL;
   struct sshbuf *ecdh_shared_secret;
   u_char hash[SSH_DIGEST_MAX_LENGTH];
-  int r;
+  int r = SSH_ERR_INTERNAL_ERROR;
   *server_blobp = NULL;
   *shared_secretp = NULL;
 
@@ -220,6 +220,7 @@ static int kex_kem_generic_with_ec_enc(OQS_KEM *kem,
 
   /* generate and encrypt KEM key with client key */
   if (OQS_KEM_encaps(kem, ciphertext, kem_key, client_pub) != OQS_SUCCESS) {
+    r = SSH_ERR_LIBCRYPTO_ERROR;
     goto out;
   }
 
@@ -294,7 +295,7 @@ static int kex_kem_generic_with_ec_dec(OQS_KEM *kem,
   struct sshbuf *ecdh_shared_secret;
   struct sshbuf *ecdh_server_blob = NULL;
   u_char hash[SSH_DIGEST_MAX_LENGTH];
-  int r;
+  int r = SSH_ERR_INTERNAL_ERROR;
   *shared_secretp = NULL;
 
   /* server_blob contains both KEM and ECDH server keys */
@@ -319,6 +320,7 @@ static int kex_kem_generic_with_ec_dec(OQS_KEM *kem,
       goto out;
     /* decapsulate the post-quantum secret */
     if (OQS_KEM_decaps(kem, kem_key, ciphertext, kex->oqs_client_key) != OQS_SUCCESS) {
+      r = SSH_ERR_LIBCRYPTO_ERROR;
       goto out;
     }
 

kexoqsx25519.c

@@ -82,7 +82,7 @@ static int kex_kem_generic_with_x25519_enc(OQS_KEM *kem, struct kex *kex,
   u_char server_key[CURVE25519_SIZE];
   u_char hash[SSH_DIGEST_MAX_LENGTH];
   size_t needed = 0;
-  int r;
+  int r = SSH_ERR_INTERNAL_ERROR;
 
   *server_blobp = NULL;
   *shared_secretp = NULL;
@@ -116,6 +116,7 @@ static int kex_kem_generic_with_x25519_enc(OQS_KEM *kem, struct kex *kex,
   /* generate and encrypt KEM key with client key */
   if (OQS_KEM_encaps(kem, public_key, private_key, client_pub)
       != OQS_SUCCESS) {
+    r = SSH_ERR_LIBCRYPTO_ERROR;
     goto out;
   }
   client_pub += kem->length_public_key;
@@ -162,7 +163,7 @@ static int kex_kem_generic_with_x25519_dec(OQS_KEM *kem, struct kex *kex,
   size_t needed = 0;
   /* x25519 values */
   u_char hash[SSH_DIGEST_MAX_LENGTH];
-  int r;
+  int r = SSH_ERR_INTERNAL_ERROR;
 
   *shared_secretp = NULL;
 
@@ -183,6 +184,7 @@ static int kex_kem_generic_with_x25519_dec(OQS_KEM *kem, struct kex *kex,
   /* decapsulate the post-quantum secret */
   if (OQS_KEM_decaps(kem, private_key, public_key,
                      kex->oqs_client_key) != OQS_SUCCESS) {
+    r = SSH_ERR_LIBCRYPTO_ERROR;
     goto out;
   }
   public_key += kem->length_ciphertext;