KEYS: put keyring if install_session_keyring_to_cred() fails

In join_session_keyring(), if install_session_keyring_to_cred() were to
fail, we would leak the keyring reference, just like in the bug fixed by
commit 23567fd052a9 ("KEYS: Fix keyring ref leak in
join_session_keyring()").  Fortunately this cannot happen currently, but
we really should be more careful.  Do this by adding and using a new
error label at which the keyring reference is dropped.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 2217dfec7996..86bced9fdbdf 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -809,15 +809,14 @@ long join_session_keyring(const char *name)
                 ret = PTR_ERR(keyring);
                 goto error2;
         } else if (keyring == new->session_keyring) {
-                key_put(keyring);
                 ret = 0;
-                goto error2;
+                goto error3;
         }
 
         /* we've got a keyring - now to install it */
         ret = install_session_keyring_to_cred(new, keyring);
         if (ret < 0)
-                goto error2;
+                goto error3;
 
         commit_creds(new);
         mutex_unlock(&key_session_mutex);
@@ -827,6 +826,8 @@ long join_session_keyring(const char *name)
 okay:
         return ret;
 
+error3:
+        key_put(keyring);
 error2:
         mutex_unlock(&key_session_mutex);
 error: