CMS_ContentInfo_free(): fix mem leak on encrypted content key

Fixes #21026

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David von Oheimb <david.von.oheimb@siemens.com>
(Merged from #21058)

(cherry picked from commit 7a18574)

crypto/cms/cms_env.c

@@ -142,10 +142,12 @@ CMS_EncryptedContentInfo *ossl_cms_get0_env_enc_content(const CMS_ContentInfo *c
 {
     switch (cms_get_enveloped_type(cms)) {
     case CMS_ENVELOPED_STANDARD:
-        return cms->d.envelopedData->encryptedContentInfo;
+        return cms->d.envelopedData == NULL ? NULL
+            : cms->d.envelopedData->encryptedContentInfo;
 
     case CMS_ENVELOPED_AUTH:
-        return cms->d.authEnvelopedData->authEncryptedContentInfo;
+        return cms->d.authEnvelopedData == NULL ? NULL
+            : cms->d.authEnvelopedData->authEncryptedContentInfo;
 
     default:
         return NULL;

crypto/cms/cms_lib.c

@@ -76,6 +76,10 @@ CMS_ContentInfo *CMS_ContentInfo_new(void)
 void CMS_ContentInfo_free(CMS_ContentInfo *cms)
 {
     if (cms != NULL) {
+        CMS_EncryptedContentInfo *ec = ossl_cms_get0_env_enc_content(cms);
+
+        if (ec != NULL)
+            OPENSSL_clear_free(ec->key, ec->keylen);
         OPENSSL_free(cms->ctx.propq);
         ASN1_item_free((ASN1_VALUE *)cms, ASN1_ITEM_rptr(CMS_ContentInfo));
     }