In the Linux kernel, the following vulnerability has been resolved: iio: adc: spear: Initialize completion before requesting IRQ In the re

In the Linux kernel, the following vulnerability has been resolved:

iio: adc: spear: Initialize completion before requesting IRQ

In the report from Jaeyoung Chung:

"spear_adc_probe() in drivers/iio/adc/spear_adc.c registers its
interrupt handler with devm_request_irq() before it initializes
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 spear_adc_probe():

 1iodev = devm_iio_device_alloc(&pdev->dev, sizeof(*st)); /* st kzalloc-zeroed */
 2...
 3retval = devm_request_irq(&pdev->dev, irq, spear_adc_isr, 0,
 4                          LPC32XXAD_NAME, st);           /* register handler */
 5...
 6init_completion(&st->completion);                       /* initialize completion */

spear_adc_isr() calls complete():

 1complete(&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."

Fix the chance of a spurious IRQ causing an uninitialized pointer
dereference by moving init_completion() above devm_request_irq().