In `waveform_common_attach()`, the two timers `&devpriv->ai_timer` and `&devpriv->ao_timer` are initialized after the allocation of the device private data by `comedi_alloc_devpriv()` and the subdevices by `comedi_alloc_subdevices()`. The function may return with an error between those function calls. In that case, `waveform_detach()` will be called by the Comedi core to clean up. The check that `waveform_detach()` uses to decide whether to delete the timers is incorrect. It only checks that the device private data was allocated, but that does not guarantee that the timers were initialized. It also needs to check that the subdevices were allocated. Fix it.

Fixes: 73e0e4dfed4c ("staging: comedi: comedi_test: fix timer lock-up") Cc: stable@vger.kernel.org # 6.15+ Signed-off-by: Ian Abbott abbotti@mev.co.uk --- Patch fails to apply to kernels before 6.15, requiring backports. --- drivers/comedi/drivers/comedi_test.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/comedi/drivers/comedi_test.c b/drivers/comedi/drivers/comedi_test.c index 9747e6d1f6eb..7984950f0f99 100644 --- a/drivers/comedi/drivers/comedi_test.c +++ b/drivers/comedi/drivers/comedi_test.c @@ -792,7 +792,7 @@ static void waveform_detach(struct comedi_device *dev) { struct waveform_private *devpriv = dev->private;

- if (devpriv) { + if (devpriv && dev->n_subdevices) { timer_delete_sync(&devpriv->ai_timer); timer_delete_sync(&devpriv->ao_timer); }