Add deep copy of propq field in mac_dupctx to avoid double free

mac_dupctx() should make a copy of the propq field. Currently it
does a shallow copy which can result in a double free and crash.
The double free occurs when using a provider property string.
For example, passing in "fips=no" to SSL_CTX_new_ex() causes the
propq field to get set to that value. When mac_dupctx() and
mac_freectx() is called (ie: in SSL_write()) it ends up freeing
the reference of the original object instead of a copy.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/13926)

diff --git a/providers/implementations/signature/mac_legacy.c b/providers/implementations/signature/mac_legacy.c
index 7d23e36f2b746dea174bef407495d90732ab057b..23865830699cac6b24a194f130285269389e2edc 100644 (file)
--- a/providers/implementations/signature/mac_legacy.c
+++ b/providers/implementations/signature/mac_legacy.c
@@ -172,9 +172,13 @@ static void *mac_dupctx(void *vpmacctx)
         return NULL;
 
     *dstctx = *srcctx;
+    dstctx->propq = NULL;
     dstctx->key = NULL;
     dstctx->macctx = NULL;
 
+    if (srcctx->propq != NULL && (dstctx->propq = OPENSSL_strdup(srcctx->propq)) == NULL)
+        goto err;
+
     if (srcctx->key != NULL && !ossl_mac_key_up_ref(srcctx->key))
         goto err;
     dstctx->key = srcctx->key;