Subject: that is reference -> that is referenced
On Thu, Sep 18, 2025 at 08:11:44PM +0200, Sebastian Andrzej Siewior wrote:
> vhost_task_create() creates a task and keeps a reference to its
> task_struct. That task may exit early via a signal and its task_struct
> will be released.
> A pending vhost_task_wake() will then attempt to wake the task and
> access a task_struct which is no longer there.
>
> Acquire a reference on the task_struct while creating the thread and
> release the reference while the struct vhost_task itself is removed.
> If the task exits early due to a signal, then the vhost_task_wake() will
> still access a valid task_struct. The wake is safe and will be skipped
> in this case.
>
> Fixes: f9010dbdce911 ("fork, vhost: Use CLONE_THREAD to fix freezer/ps
> regression")
> Reported-by: Sean Christopherson <[email protected]>
> Closes: https://lore.kernel.org/all/[email protected]/
> Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
> ---
> kernel/vhost_task.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/vhost_task.c b/kernel/vhost_task.c
> index bc738fa90c1d6..27107dcc1cbfe 100644
> --- a/kernel/vhost_task.c
> +++ b/kernel/vhost_task.c
> @@ -100,6 +100,7 @@ void vhost_task_stop(struct vhost_task *vtsk)
> * freeing it below.
> */
> wait_for_completion(&vtsk->exited);
> + put_task_struct(vtsk->task);
> kfree(vtsk);
> }
> EXPORT_SYMBOL_GPL(vhost_task_stop);
> @@ -148,7 +149,7 @@ struct vhost_task *vhost_task_create(bool (*fn)(void *),
> return ERR_CAST(tsk);
> }
>
> - vtsk->task = tsk;
> + vtsk->task = get_task_struct(tsk);
> return vtsk;
> }
> EXPORT_SYMBOL_GPL(vhost_task_create);
> --
> 2.51.0
