Fix memory leak in EVP_PKEY_get1_encoded_public_key.

Occurs if a failure happens after the malloc call in the second call to
EVP_PKEY_get_octet_string_param().

Detected by PR #18355

Some calling code assumes that nothing is allocated in the returned
pointer if there was a failure. Other calling code always trys freeing.
The third case is in ecdh_cms_encrypt() where it does not check the
return value. I am assuming this change is ok since the legacy path in
EVP_PKEY_get1_encoded_public_key() also does not return the pointer on
failure.

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18739)

diff --git a/crypto/evp/p_lib.c b/crypto/evp/p_lib.c
index 8d2eee11f1a94eb0cd620626dc08762b52eb4b5d..aef63128f95b4a4a8aefb95f4a2ac90a7f84dd60 100644 (file)
--- a/crypto/evp/p_lib.c
+++ b/crypto/evp/p_lib.c
@@ -1389,6 +1389,7 @@ size_t EVP_PKEY_get1_encoded_public_key(EVP_PKEY *pkey, unsigned char **ppub)
 
     if (pkey != NULL && evp_pkey_is_provided(pkey)) {
         size_t return_size = OSSL_PARAM_UNMODIFIED;
+        unsigned char *buf;
 
         /*
          * We know that this is going to fail, but it will give us a size
@@ -1400,14 +1401,18 @@ size_t EVP_PKEY_get1_encoded_public_key(EVP_PKEY *pkey, unsigned char **ppub)
         if (return_size == OSSL_PARAM_UNMODIFIED)
             return 0;
 
-        *ppub = OPENSSL_malloc(return_size);
-        if (*ppub == NULL)
+        *ppub = NULL;
+        buf = OPENSSL_malloc(return_size);
+        if (buf == NULL)
             return 0;
 
         if (!EVP_PKEY_get_octet_string_param(pkey,
                                              OSSL_PKEY_PARAM_ENCODED_PUBLIC_KEY,
-                                             *ppub, return_size, NULL))
+                                             buf, return_size, NULL)) {
+            OPENSSL_free(buf);
             return 0;
+        }
+        *ppub = buf;
         return return_size;
     }