provider_core: sort provider stack on find

Adding all providers is quadratic time because each provider is checked
for being in the stack before adding it.  However, this is an improvement
over the older O(n^2 log n) code where each find also sorted the stack.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Todd Short <todd.short@me.com>
(Merged from https://github.com/openssl/openssl/pull/20842)

diff --git a/crypto/provider_core.c b/crypto/provider_core.c
index 246667ecb218c2527538e3ec3f09da05f503b957..60a1efedfbeb4e3f57245c3918a0365f4feeecbf 100644 (file)
--- a/crypto/provider_core.c
+++ b/crypto/provider_core.c
@@ -417,12 +417,9 @@ OSSL_PROVIDER *ossl_provider_find(OSSL_LIB_CTX *libctx, const char *name,
 #endif
 
         tmpl.name = (char *)name;
-        /*
-         * A "find" operation can sort the stack, and therefore a write lock is
-         * required.
-         */
         if (!CRYPTO_THREAD_write_lock(store->lock))
             return NULL;
+        sk_OSSL_PROVIDER_sort(store->providers);
         if ((i = sk_OSSL_PROVIDER_find(store->providers, &tmpl)) != -1)
             prov = sk_OSSL_PROVIDER_value(store->providers, i);
         CRYPTO_THREAD_unlock(store->lock);