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comedi: comedi_test: Fix possible deletion of uninitialized timers

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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: 73e0e4dfed ("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>
This commit is contained in:
Ian Abbott 2025-07-08 14:06:27 +01:00 • committed by Greg Kroah-Hartman
parent 46d8c74413
commit 1b98304c09
1 changed files with 1 additions and 1 deletions
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2
drivers/comedi/drivers/comedi_test.c
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@ -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);
}