From 451c43bb4c762ba5d54fb13747e7c0a1b77a8da7 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Tue, 8 Jul 2025 14:06:27 +0100 Subject: [PATCH] comedi: comedi_test: Fix possible deletion of uninitialized timers commit 1b98304c09a0192598d0767f1eb8c83d7e793091 upstream. 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 Link: https://lore.kernel.org/r/20250708130627.21743-1-abbotti@mev.co.uk [ file location from drivers/comedi to drivers/staging/comedi and timer_delete_sync() to del_timer_sync(). ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- 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); }