Return NULL from ossl_lib_ctx_get_concrete() when it is uninitialized

When default_context_inited is set to false we return NULL instead of
the global default context.

Fixes #25442

Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/26319)

2 files changed, 16 insertions, 4 deletions

diff --git a/crypto/context.c b/crypto/context.c
index 96216abcda..9bb0577adf 100644
--- a/crypto/context.c
+++ b/crypto/context.c
@@ -57,17 +57,23 @@ struct ossl_lib_ctx_st {
 
 int ossl_lib_ctx_write_lock(OSSL_LIB_CTX *ctx)
 {
-    return CRYPTO_THREAD_write_lock(ossl_lib_ctx_get_concrete(ctx)->lock);
+    if ((ctx = ossl_lib_ctx_get_concrete(ctx)) == NULL)
+        return 0;
+    return CRYPTO_THREAD_write_lock(ctx->lock);
 }
 
 int ossl_lib_ctx_read_lock(OSSL_LIB_CTX *ctx)
 {
-    return CRYPTO_THREAD_read_lock(ossl_lib_ctx_get_concrete(ctx)->lock);
+    if ((ctx = ossl_lib_ctx_get_concrete(ctx)) == NULL)
+        return 0;
+    return CRYPTO_THREAD_read_lock(ctx->lock);
 }
 
 int ossl_lib_ctx_unlock(OSSL_LIB_CTX *ctx)
 {
-    return CRYPTO_THREAD_unlock(ossl_lib_ctx_get_concrete(ctx)->lock);
+    if ((ctx = ossl_lib_ctx_get_concrete(ctx)) == NULL)
+        return 0;
+    return CRYPTO_THREAD_unlock(ctx->lock);
 }
 
 int ossl_lib_ctx_is_child(OSSL_LIB_CTX *ctx)
@@ -421,7 +427,7 @@ static OSSL_LIB_CTX *get_default_context(void)
 {
     OSSL_LIB_CTX *current_defctx = get_thread_default_context();
 
-    if (current_defctx == NULL)
+    if (current_defctx == NULL && default_context_inited)
         current_defctx = &default_context_int;
     return current_defctx;
 }
diff --git a/crypto/rand/rand_lib.c b/crypto/rand/rand_lib.c
index ad66cd7791..a15614faa5 100644
--- a/crypto/rand/rand_lib.c
+++ b/crypto/rand/rand_lib.c
@@ -818,6 +818,9 @@ EVP_RAND_CTX *RAND_get0_public(OSSL_LIB_CTX *ctx)
             return NULL;
 
         ctx = ossl_lib_ctx_get_concrete(ctx);
+
+        if (ctx == NULL)
+            return NULL;
         /*
          * If the private is also NULL then this is the first time we've
          * used this thread.
@@ -851,6 +854,9 @@ EVP_RAND_CTX *RAND_get0_private(OSSL_LIB_CTX *ctx)
             return NULL;
 
         ctx = ossl_lib_ctx_get_concrete(ctx);
+
+        if (ctx == NULL)
+            return NULL;
         /*
          * If the public is also NULL then this is the first time we've
          * used this thread.