3 files changed, 13 insertions, 20 deletions

diff --git a/security/keys/internal.h b/security/keys/internal.h
index c990b8c8ef1d..22ff05269e3d 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -149,7 +149,7 @@ extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
 #define KEY_LOOKUP_FOR_UNLINK   0x04
 
 extern long join_session_keyring(const char *name);
-extern void key_change_session_keyring(struct task_work *twork);
+extern void key_change_session_keyring(struct callback_head *twork);
 
 extern struct work_struct key_gc_work;
 extern unsigned key_gc_delay;
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 3bdc419b272f..3364fbf46807 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1456,7 +1456,7 @@ long keyctl_session_to_parent(void)
 {
         struct task_struct *me, *parent;
         const struct cred *mycred, *pcred;
-        struct task_work *newwork, *oldwork;
+        struct callback_head *newwork, *oldwork;
         key_ref_t keyring_r;
         struct cred *cred;
         int ret;
@@ -1466,19 +1466,17 @@ long keyctl_session_to_parent(void)
                 return PTR_ERR(keyring_r);
 
         ret = -ENOMEM;
-        newwork = kmalloc(sizeof(struct task_work), GFP_KERNEL);
-        if (!newwork)
-                goto error_keyring;
 
         /* 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 */
         cred = cred_alloc_blank();
         if (!cred)
-                goto error_newwork;
+                goto error_keyring;
+        newwork = &cred->rcu;
 
         cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
-        init_task_work(newwork, key_change_session_keyring, cred);
+        init_task_work(newwork, key_change_session_keyring);
 
         me = current;
         rcu_read_lock();
@@ -1488,6 +1486,7 @@ long keyctl_session_to_parent(void)
         oldwork = NULL;
         parent = me->real_parent;
 
+        task_lock(parent);
         /* the parent mustn't be init and mustn't be a kernel thread */
         if (parent->pid <= 1 || !parent->mm)
                 goto unlock;
@@ -1531,20 +1530,15 @@ long keyctl_session_to_parent(void)
         if (!ret)
                 newwork = NULL;
 unlock:
+        task_unlock(parent);
         write_unlock_irq(&tasklist_lock);
         rcu_read_unlock();
-        if (oldwork) {
-                put_cred(oldwork->data);
-                kfree(oldwork);
-        }
-        if (newwork) {
-                put_cred(newwork->data);
-                kfree(newwork);
-        }
+        if (oldwork)
+                put_cred(container_of(oldwork, struct cred, rcu));
+        if (newwork)
+                put_cred(cred);
         return ret;
 
-error_newwork:
-        kfree(newwork);
 error_keyring:
         key_ref_put(keyring_r);
         return ret;
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 4ad54eea1ea4..54339cfd6734 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -834,12 +834,11 @@ error:
  * Replace a process's session keyring on behalf of one of its children when
  * the target  process is about to resume userspace execution.
  */
-void key_change_session_keyring(struct task_work *twork)
+void key_change_session_keyring(struct callback_head *twork)
 {
         const struct cred *old = current_cred();
-        struct cred *new = twork->data;
+        struct cred *new = container_of(twork, struct cred, rcu);
 
-        kfree(twork);
         if (unlikely(current->flags & PF_EXITING)) {
                 put_cred(new);
                 return;