KEYS: fix key refcount leak in keyctl_assume_authority()
authorEric Biggers <ebiggers@google.com>
Mon, 18 Sep 2017 18:36:12 +0000 (11:36 -0700)
committerDavid Howells <dhowells@redhat.com>
Mon, 25 Sep 2017 14:19:57 +0000 (15:19 +0100)
commit884bee0215fcc239b30c062c37ca29077005e064
treee74b9a72d9bdffcc459d8a0393a6f908ef4d213a
parentf7b48cf08fa63a68b59c2894806ee478216d7f91
KEYS: fix key refcount leak in keyctl_assume_authority()

In keyctl_assume_authority(), if keyctl_change_reqkey_auth() were to
fail, we would leak the reference to the 'authkey'.  Currently this can
only happen if prepare_creds() fails to allocate memory.  But it still
should be fixed, as it is a more severe bug waiting to happen.

This patch also moves the read of 'authkey->serial' to before the
reference to the authkey is dropped.  Doing the read after dropping the
reference is very fragile because it assumes we still hold another
reference to the key.  (Which we do, in current->cred->request_key_auth,
but there's no reason not to write it in the "obviously correct" way.)

Fixes: d84f4f992cbd ("CRED: Inaugurate COW credentials")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
security/keys/keyctl.c