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KEYS: fix key refcount leak in keyctl_assume_authority()

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commit 884bee0215 upstream.

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: d84f4f992c ("CRED: Inaugurate COW credentials")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Eric Biggers
2017-09-18 11:36:12 -07:00
committed by Ben Hutchings
parent 9e90392640
commit 4955da6650
1 changed files with 2 additions and 4 deletions
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6
security/keys/keyctl.c
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@ -1345,11 +1345,9 @@ long keyctl_assume_authority(key_serial_t id)
}
ret = keyctl_change_reqkey_auth(authkey);
if (ret < 0)
goto error;
if (ret == 0)
ret = authkey->serial;
key_put(authkey);
ret = authkey->serial;
error:
return ret;
}