QCryptographicHash: don't forget to unload OpenSSL providers

Automatically unload loaded crypto providers on cleanup. In most cases
we don't load them, but when we do (e.g. when MD4 is used), we would be
leaking memory.

Fixes: QTBUG-115233
Pick-to: 6.5 6.6
Change-Id: I91318d391ab35d00647d1e9e2408fc987811a2d3
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 15 insertions, 5 deletions

diff --git a/src/corelib/tools/qcryptographichash.cpp b/src/corelib/tools/qcryptographichash.cpp
index 6986601b9f..bec5cf9df1 100644
--- a/src/corelib/tools/qcryptographichash.cpp
+++ b/src/corelib/tools/qcryptographichash.cpp
@@ -326,11 +326,20 @@ public:
             EVP_MD_free(md);
         }
     };
+    struct OSSL_PROVIDER_deleter {
+        void operator()(OSSL_PROVIDER *provider) const noexcept {
+            OSSL_PROVIDER_unload(provider);
+        }
+    };
+
     using EVP_MD_CTX_ptr = std::unique_ptr<EVP_MD_CTX, EVP_MD_CTX_deleter>;
     using EVP_MD_ptr = std::unique_ptr<EVP_MD, EVP_MD_deleter>;
+    using OSSL_PROVIDER_ptr = std::unique_ptr<OSSL_PROVIDER, OSSL_PROVIDER_deleter>;
     struct EVP {
         EVP_MD_ptr algorithm;
         EVP_MD_CTX_ptr context;
+        OSSL_PROVIDER_ptr defaultProvider;
+        OSSL_PROVIDER_ptr legacyProvider;
         bool initializationFailed;
 
         explicit EVP(QCryptographicHash::Algorithm method);
@@ -583,9 +592,10 @@ QCryptographicHashPrivate::EVP::EVP(QCryptographicHash::Algorithm method)
          * We need to load the legacy provider in order to have the MD4
          * algorithm available.
          */
-        if (!OSSL_PROVIDER_load(nullptr, "legacy"))
-            return;
-        if (!OSSL_PROVIDER_load(nullptr, "default"))
+        legacyProvider = OSSL_PROVIDER_ptr(OSSL_PROVIDER_load(nullptr, "legacy"));
+        defaultProvider = OSSL_PROVIDER_ptr(OSSL_PROVIDER_load(nullptr, "default"));
+
+        if (!legacyProvider || !defaultProvider)
             return;
     }
 
@@ -1163,8 +1173,8 @@ bool QCryptographicHashPrivate::supportsAlgorithm(QCryptographicHash::Algorithm
     if (useNonOpenSSLFallback(method))
         return true;
 
-    OSSL_PROVIDER_load(nullptr, "legacy");
-    OSSL_PROVIDER_load(nullptr, "default");
+    auto legacyProvider = OSSL_PROVIDER_ptr(OSSL_PROVIDER_load(nullptr, "legacy"));
+    auto defaultProvider = OSSL_PROVIDER_ptr(OSSL_PROVIDER_load(nullptr, "default"));
 
     const char *restriction = "-fips";
     EVP_MD_ptr algorithm = EVP_MD_ptr(EVP_MD_fetch(nullptr, methodToName(method), restriction));