[ Upstream commit 1b98304c09a0192598d0767f1eb8c83d7e793091 ]

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 Link: https://lore.kernel.org/r/20250708130627.21743-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [ changed timer_delete_sync() to del_timer_sync() ] Signed-off-by: Ian Abbott abbotti@mev.co.uk --- drivers/staging/comedi/drivers/comedi_test.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/comedi/drivers/comedi_test.c b/drivers/staging/comedi/drivers/comedi_test.c index 9e60d2a0edc1..7397495de4d6 100644 --- a/drivers/staging/comedi/drivers/comedi_test.c +++ b/drivers/staging/comedi/drivers/comedi_test.c @@ -790,7 +790,7 @@ static void waveform_detach(struct comedi_device *dev) { struct waveform_private *devpriv = dev->private;

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