Hi,
On 18-Aug-26 10:11, Fan Wu wrote:
> VMMDEV_EVENT_BALLOON_CHANGE_REQUEST is reported only after a guest
> userspace client enables it with VBOXGUEST_IOCTL_SET_EVENT_FILTER.
> The interrupt handler then queues the balloon work, which reads and
> writes the mem_balloon.get_req and change_req request buffers.
>
> vbg_pci_remove() calls free_irq() before vbg_core_exit(), but
> free_irq() only waits for the handler to return, not for any work it
> has queued. A balloon work still running on system_wq therefore
> touches the request buffers after vbg_core_exit() has freed them:
>
> CPU 0 (remove) IRQ handler system_wq
> free_irq() schedule_work(...)
> return
> vbg_core_exit()
> vbg_req_free(...) vbg_balloon_work()
> req->event_ack = ...
>
> Fix this by calling cancel_work_sync() on mem_balloon.work in
> vbg_core_exit(), before the request buffers are freed. The worker
> does not requeue itself, and the interrupt handler, the only place
> that queues it, can no longer run when vbg_core_exit() is reached:
> vbg_pci_remove() has already called free_irq(), and on the probe
> error path the irq was never requested. Draining the work once is
> therefore sufficient.
>
> This issue was found by an in-house static analysis tool.
>
> Fixes: 0ba002bc4393 ("virt: Add vboxguest driver for Virtual Box Guest
> integration")
> Cc: [email protected]
> Assisted-by: Codex:gpt-5.6
> Signed-off-by: Fan Wu <[email protected]>
Thanks, patch looks good to me:
Reviewed-by: Hans de Goede <[email protected]>
Regards,
Hans
> ---
> drivers/virt/vboxguest/vboxguest_core.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/virt/vboxguest/vboxguest_core.c
> b/drivers/virt/vboxguest/vboxguest_core.c
> index b177a534b6a4..884e69d00f72 100644
> --- a/drivers/virt/vboxguest/vboxguest_core.c
> +++ b/drivers/virt/vboxguest/vboxguest_core.c
> @@ -1048,6 +1048,8 @@ int vbg_core_init(struct vbg_dev *gdev, u32
> fixed_events)
> */
> void vbg_core_exit(struct vbg_dev *gdev)
> {
> + cancel_work_sync(&gdev->mem_balloon.work);
> +
> vbg_heartbeat_exit(gdev);
> vbg_guest_mappings_exit(gdev);
>
