On Mon, 8 Feb 2021 23:39:47 +0100 Petr Štetiar ynezz@true.cz wrote:

My machine Oopsed while testing SCD30 sensor in interrupt driven mode:

Unable to handle kernel NULL pointer dereference at virtual address 00000188 pgd = (ptrval) [00000188] *pgd=00000000 Internal error: Oops: 5 [#1] SMP ARM Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.96+ #473 Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree) PC is at _raw_spin_lock_irqsave+0x10/0x4c LR is at devres_add+0x18/0x38 ... [<8070ecac>] (_raw_spin_lock_irqsave) from [<804916a8>] (devres_add+0x18/0x38) [<804916a8>] (devres_add) from [<805ef708>] (devm_iio_trigger_alloc+0x5c/0x7c) [<805ef708>] (devm_iio_trigger_alloc) from [<805f0a90>] (scd30_probe+0x1d4/0x3f0) [<805f0a90>] (scd30_probe) from [<805f10fc>] (scd30_i2c_probe+0x54/0x64) [<805f10fc>] (scd30_i2c_probe) from [<80583390>] (i2c_device_probe+0x150/0x278) [<80583390>] (i2c_device_probe) from [<8048e6c0>] (really_probe+0x1f8/0x360)

I've found out, that it's due to missing parent/owner device in iio_dev struct which then leads to NULL pointer dereference during spinlock while registering the device resource via devres_add().

Cc: stable@vger.kernel.org # v5.9+ Fixes: 64b3d8b1b0f5 ("iio: chemical: scd30: add core driver") Signed-off-by: Petr Štetiar ynezz@true.cz

Hi Petr,

So, we moved this into the core a while back (to avoid exactly this sort of issue). That change predates this introduction of this driver as it went in in v5.8

So I think you've hit an issue with a backport here to an earlier kernel?

Jonathan

---

drivers/iio/chemical/scd30_core.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/drivers/iio/chemical/scd30_core.c b/drivers/iio/chemical/scd30_core.c index 4d0d798c7cd3..33aa6eb1963d 100644 --- a/drivers/iio/chemical/scd30_core.c +++ b/drivers/iio/chemical/scd30_core.c @@ -697,6 +697,7 @@ int scd30_probe(struct device *dev, int irq, const char *name, void *priv, dev_set_drvdata(dev, indio_dev);

• indio_dev->dev.parent = dev; indio_dev->info = &scd30_info; indio_dev->name = name; indio_dev->channels = scd30_channels;