diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2025-09-18 20:11:44 +0200 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2025-09-21 17:44:20 -0400 |
| commit | afe16653e05db07d658b55245c7a2e0603f136c0 (patch) | |
| tree | 3d0b4e6a3219818a4a676472d4851d04875437f3 | |
| parent | e430451613c7a27beeadd00d707bcf7ceec6328e (diff) | |
vhost: Take a reference on the task in struct vhost_task.
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 <seanjc@google.com>
Closes: https://lore.kernel.org/all/aKkLEtoDXKxAAWju@google.com/
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Message-Id: <20250918181144.Ygo8BZ-R@linutronix.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | kernel/vhost_task.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/vhost_task.c b/kernel/vhost_task.c index bc738fa90c1d..27107dcc1cbf 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); |