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SubjectRe: [PATCH 4/4] task_work: kill task_work->data
On 06/27, Oleg Nesterov wrote:
>
> Turn cred->rcu into rcu_head/task_work union for keyctl_session_to_parent().

I tried to make the minimal patch, but perhaps with this change we
can also simplify the error handling in keyctl_session_to_parent()
a little bit.

We can do cred_alloc_blank() before lookup_user_key() and remove
error_keyring/key_ref_put.

IOW, on top of this patch:

--- x/security/keys/keyctl.c
+++ x/security/keys/keyctl.c
@@ -1461,17 +1461,18 @@ long keyctl_session_to_parent(void)
struct cred *cred;
int ret;

- keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_LINK);
- if (IS_ERR(keyring_r))
- return PTR_ERR(keyring_r);
-
/* our parent is going to need a new cred struct, a new tgcred struct
* and new security data, so we allocate them here to prevent ENOMEM in
* our parent */
- ret = -ENOMEM;
cred = cred_alloc_blank();
if (!cred)
- goto error_keyring;
+ return -ENOMEM;
+
+ keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_LINK);
+ if (IS_ERR(keyring_r)) {
+ ret = PTR_ERR(keyring_r);
+ goto free_cred;
+ }

cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
init_task_work(&cred->twork, key_change_session_keyring);
@@ -1532,13 +1533,10 @@ unlock:

if (oldwork)
put_cred(container_of(oldwork, struct cred, twork));
+free_cred:
if (cred)
put_cred(cred);
return ret;
-
-error_keyring:
- key_ref_put(keyring_r);
- return ret;
}

/*


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