provider: free the child libctx on teardown

.github/workflows/README.md

@@ -251,14 +251,14 @@ wolfProvider and the test is dead weight.
 
 | Job | Flags | What it catches |
 |-----|-------|-----------------|
-| `sanitizers` (ASan + UBSan) | `-fsanitize=address,undefined -fno-omit-frame-pointer -fno-sanitize-recover=all` | use-after-free, double-free, out-of-bounds read/write, signed overflow, misaligned access, NULL deref, etc. |
+| `sanitizers` (ASan + UBSan) | `-fsanitize=address,undefined -fno-omit-frame-pointer -fno-sanitize-recover=all` | use-after-free, double-free, out-of-bounds read/write, signed overflow, misaligned access, NULL deref, etc.; leaks in `make test` (LeakSanitizer). |
 | `tsan` (Thread Sanitizer) | `-fsanitize=thread` | data races + lock-ordering violations in the multi-threaded unit tests in `test/unit.c` (`pthread_create` fan-out). |
 
 ASan and TSan can't coexist in one binary, so they're separate jobs
-with separate caches. Both use `LD_PRELOAD=libasan.so` / `libtsan.so`
-for the unit-test run because wolfProvider is loaded via `dlopen()`
-from OpenSSL and the runtime needs the sanitizer interceptors live
-before any provider code runs. `ASAN_OPTIONS=detect_odr_violation=0`
+with separate caches. The unit-test binaries link the sanitizer
+runtime. The ASan job preloads `libasan.so` only for `scripts/env-setup`
+and the cmd-tests, and runs `make test` with `detect_leaks=1`.
+`ASAN_OPTIONS=detect_odr_violation=0`
 is set to suppress a known false positive from the provider's static
 ASN.1 table being linked into both `libwolfprov.so` and the test
 binary.

.github/workflows/sanitizers.yml

@@ -51,7 +51,8 @@ jobs:
       matrix:
         wolfssl_ref: ${{ fromJson(needs.discover_versions.outputs.wolfssl_latest_ref_array) }}
     env:
-      # detect_leaks=0: OpenSSL keeps provider-registry allocs alive.
+      # detect_leaks=0: the libasan preload would also leak-check shell
+      # tools; the unit-test step enables it for the test binaries only.
       # detect_odr_violation=0: libwolfprov is linked + dlopen'd in
       # test/unit.test -- false-positive ODR.
       ASAN_OPTIONS: detect_leaks=0:halt_on_error=1:abort_on_error=0:print_stacktrace=1:detect_odr_violation=0
@@ -111,7 +112,9 @@ jobs:
         run: |
           export LD_PRELOAD="$(gcc -print-file-name=libasan.so)"
           source scripts/env-setup
-          make test
+          # Preload is only for env-setup's openssl; test binaries link libasan.
+          unset LD_PRELOAD
+          ASAN_OPTIONS="${ASAN_OPTIONS}:detect_leaks=1" make test
 
       - name: Run cmd-tests under sanitizers
         shell: bash

include/wolfprovider/internal.h

@@ -153,7 +153,7 @@ enum {
 typedef struct WOLFPROV_CTX {
     /** Cached handle to a resource. */
     const OSSL_CORE_HANDLE *handle;
-    /** Library context to use in all cases. */
+    /** Library context to use in all cases. Owned; may be NULL. */
     OSSL_LIB_CTX *libCtx;
    /** Random number generator. */
    WC_RNG rng;

src/wp_wolfprov.c

@@ -285,6 +285,7 @@ static WOLFPROV_CTX* wolfssl_prov_ctx_new(void)
  */
 static void wolfssl_prov_ctx_free(WOLFPROV_CTX* ctx)
 {
+    OSSL_LIB_CTX_free(ctx->libCtx);
 #if defined(WP_HAVE_SEED_SRC) && defined(WP_HAVE_RANDOM)
     /* Release a reference only if this context took one; pairing a failed init
      * with a cleanup would tear down the shared subsystem other contexts use. */
@@ -310,7 +311,7 @@ static void wolfssl_prov_ctx_free(WOLFPROV_CTX* ctx)
  * Stores the library context object in the wolfSSL provider object.
  *
  * @param [in] ctx     wolfSSL provider context object.
- * @param [in] libCtx  Library context object.
+ * @param [in] libCtx  Library context object. Owned by ctx.
  */
 static void wolfssl_prov_ctx_set0_lib_ctx(WOLFPROV_CTX* ctx,
         OSSL_LIB_CTX* libCtx)