Fix a possible memory leak in SM2 provider

ctx->propq that strdup from input parameter propq in sm2sig_newctx,
is not released. It should be released in sm2sig_freectx and copied
to dstctx in sm2sig_dupctx. And dstctx->id and dstctx->propq should
be set NULL to avoid releasing id/propq of srcctx when err occurs.

Signed-off-by: Huiyue Xu <xuhuiyue@huawei.com>

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Yang <kaishen.yy@antfin.com>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
(Merged from #22796)

providers/implementations/signature/sm2_sig.c

@@ -329,6 +329,7 @@ static void sm2sig_freectx(void *vpsm2ctx)
 
     free_md(ctx);
     EC_KEY_free(ctx->ec);
+    OPENSSL_free(ctx->propq);
     OPENSSL_free(ctx->id);
     OPENSSL_free(ctx);
 }
@@ -344,13 +345,21 @@ static void *sm2sig_dupctx(void *vpsm2ctx)
 
     *dstctx = *srcctx;
     dstctx->ec = NULL;
+    dstctx->propq = NULL;
     dstctx->md = NULL;
     dstctx->mdctx = NULL;
+    dstctx->id = NULL;
 
     if (srcctx->ec != NULL && !EC_KEY_up_ref(srcctx->ec))
         goto err;
     dstctx->ec = srcctx->ec;
 
+    if (srcctx->propq != NULL) {
+        dstctx->propq = OPENSSL_strdup(srcctx->propq);
+        if (dstctx->propq == NULL)
+            goto err;
+    }
+
     if (srcctx->md != NULL && !EVP_MD_up_ref(srcctx->md))
         goto err;
     dstctx->md = srcctx->md;