Re: [PATCH 0/2] iio: adc: Initialize completions before requesting IRQs

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 12 Jun 2026 19:58:09 -0500
Maxwell Doose <m32285159@gmail.com> wrote:

> Hi all,
> 
> This short patch series fixes the issues raised by Jaeyoung Chung,
> Sangyun Kim, and Kyungwook Boo regarding init_completion() and spurious
> IRQs. The report is linked below [1], but I will also put it here
> inline:
> 
> "lpc32xx_adc_probe() in drivers/iio/adc/lpc32xx_adc.c and
> spear_adc_probe() in drivers/iio/adc/spear_adc.c register their
> interrupt handler with devm_request_irq() before they initialize
> st->completion with init_completion(). If an interrupt arrives after
> devm_request_irq() and before init_completion(), the handler calls
> complete() on an uninitialized completion, causing a kernel panic.
> 
> The probe path, in lpc32xx_adc_probe():
> 
>     iodev = devm_iio_device_alloc(&pdev->dev, sizeof(*st)); /* st kzalloc-zeroed */
>     ...
>     retval = devm_request_irq(&pdev->dev, irq, lpc32xx_adc_isr, 0,
>                               LPC32XXAD_NAME, st);           /* register handler */
>     ...
>     init_completion(&st->completion);                       /* initialize completion */
> 
> spear_adc_probe() has the same ordering: devm_request_irq() for
> spear_adc_isr() before init_completion(&st->completion).
> 
> Both interrupt handlers, lpc32xx_adc_isr() and spear_adc_isr(), call
> complete():
> 
>     complete(&st->completion);
> 
> If the device raises an interrupt before init_completion() runs,
> complete() acquires the uninitialized wait.lock and walks the zeroed
> task_list in swake_up_locked(). The zeroed task_list makes list_empty()
> return false, so swake_up_locked() dereferences a NULL list entry,
> triggering a KASAN wild-memory-access.
> 
> Suggested fix: move init_completion(&st->completion) above
> devm_request_irq(), so the completion is valid before the handler can run.
> 
> Reported-by: Sangyun Kim <sangyun.kim@snu.ac.kr>
> Reported-by: Kyungwook Boo <bookyungwook@gmail.com>"
> 
> + Reported-by: Jaeyoung Chung <jjy600901@snu.ac.kr>
> 
> Quick note, I ended up editing the report a little in the individual
> commits to match the driver we were fixing.
> 
> [1] Link: https://lore.kernel.org/linux-iio/20260610115700.774689-1-jjy600901@snu.ac.kr/

Applied to the fixes-togreg branch of iio.git and marked for stable.
Note that I'll be rebasing on rc1 once available.

Thanks

Jonathan

> 
> Maxwell Doose (2):
>   iio: adc: lpc32xx: Initialize completion before requesting IRQ
>   iio: adc: spear: Initialize completion before requesting IRQ
> 
>  drivers/iio/adc/lpc32xx_adc.c | 4 ++--
>  drivers/iio/adc/spear_adc.c   | 3 +--
>  2 files changed, 3 insertions(+), 4 deletions(-)
>