commit c1c1783d45a5e91951e6328a820939d0256c841c
author Richard Levitte <levitte@openssl.org> Thu May 17 09:53:14 2018 +0200
committer Richard Levitte <levitte@openssl.org> Sun May 20 09:48:58 2018 +0200
tree ca4dbeb0f18d205dfb3f67871bc56f038a81cb4e
parent f3021aca4a154c2ff9bd0030f7974eb6a719550d

Restore check of |*xn| against |name| in X509_NAME_set

A previous change of this function introduced a fragility when the
destination happens to be the same as the source.  Such alias isn't
recommended, but could still happen, for example in this kind of code:

    X509_NAME *subject = X509_get_issuer_name(x);

    /* ... some code passes ... */

    X509_set_issuer_name(x, subject);

Fixes #4710

Reviewed-by: Andy Polyakov <appro@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6280)

crypto/x509/x_name.c

diff --git a/crypto/x509/x_name.c b/crypto/x509/x_name.c
index aec3459..a1e9bbd 100644
--- a/crypto/x509/x_name.c
+++ b/crypto/x509/x_name.c
@@ -481,6 +481,8 @@
 
 int X509_NAME_set(X509_NAME **xn, X509_NAME *name)
 {
+    if (*xn == name)
+        return *xn != NULL;
     if ((name = X509_NAME_dup(name)) == NULL)
         return 0;
     X509_NAME_free(*xn);