Re: [PATCH] vhost: Take a reference on the task that is reference in struct vhost_task.
From: Sean Christopherson <seanjc@google.com>
Date: 2025-09-19 21:15:47
Also in:
kvm, lkml, virtualization
On Thu, Sep 18, 2025, 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 <seanjc@google.com>
Closes: https://lore.kernel.org/all/aKkLEtoDXKxAAWju@google.com/ (local)
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---Tested-by: Sean Christopherson <seanjc@google.com>