Assert that a property definition cache entry is the first

When adding a property definition cache entry for a given property query
string we add an assert that we are not replacing an existing entry. If we
are then that indicates a bug in the caller.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Todd Short <todd.short@me.com>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18458)

diff --git a/crypto/property/defn_cache.c b/crypto/property/defn_cache.c
index 282d43c80ac34495c16d96ff464b134a52ce4259..c697e6f474f7f12b46bdaa226aee8c44a864ac6e 100644 (file)
--- a/crypto/property/defn_cache.c
+++ b/crypto/property/defn_cache.c
@@ -79,6 +79,11 @@ OSSL_PROPERTY_LIST *ossl_prop_defn_get(OSSL_LIB_CTX *ctx, const char *prop)
     return r != NULL ? r->defn : NULL;
 }
 
+/*
+ * Cache the property list for a given property string. Callers of this function
+ * should call ossl_prop_defn_get first to ensure that there is no existing
+ * cache entry for this property string.
+ */
 int ossl_prop_defn_set(OSSL_LIB_CTX *ctx, const char *prop,
                        OSSL_PROPERTY_LIST *pl)
 {
@@ -109,8 +114,14 @@ int ossl_prop_defn_set(OSSL_LIB_CTX *ctx, const char *prop,
         p->defn = pl;
         memcpy(p->body, prop, len + 1);
         old = lh_PROPERTY_DEFN_ELEM_insert(property_defns, p);
-        if (old != NULL) {
-            property_defn_free(old);
+        if (!ossl_assert(old == NULL)) {
+            /*
+             * This should not happen. Any caller of ossl_prop_defn_set should
+             * have called ossl_prop_defn_get first - so we should know that
+             * there is no existing entry. If we get here we have a bug. We
+             * deliberately leak the |old| reference in order to avoid a crash
+             * if there are any existing users of it.
+             */
             goto end;
         }
         if (!lh_PROPERTY_DEFN_ELEM_error(property_defns))