| Message ID | 20230719083208.88149-1-mzamazal@redhat.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v3] iio: core: Prevent invalid memory access when there is no parent | expand |
On Wed, Jul 19, 2023 at 10:32:08AM +0200, Milan Zamazal wrote: > Changes in v3: > - The call trace in the commit message reduced to the minimum lines > needed to explain the problem. Precisely, that deserves my tag which I already had given :-) Thank you!
On Wed, 19 Jul 2023 18:27:45 +0300 Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote: > On Wed, Jul 19, 2023 at 10:32:08AM +0200, Milan Zamazal wrote: > > > Changes in v3: > > - The call trace in the commit message reduced to the minimum lines > > needed to explain the problem. > > Precisely, that deserves my tag which I already had given :-) > Thank you! > Applied to the fixes-togreg branch of iio.git. In theory every device should have a parent, but this fix is more minimal than adding one for the dummy device (which we should still do - even if it's a virtual device of some type that we create just for this purpose). That reminds me, I was in process of fixing this for perf drivers and forgot to finish it off :) Jonathan
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index c117f50d0cf3..adcba832e6fa 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -1888,7 +1888,7 @@ static const struct iio_buffer_setup_ops noop_ring_setup_ops; int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod) { struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev); - struct fwnode_handle *fwnode; + struct fwnode_handle *fwnode = NULL; int ret; if (!indio_dev->info) @@ -1899,7 +1899,8 @@ int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod) /* If the calling driver did not initialize firmware node, do it here */ if (dev_fwnode(&indio_dev->dev)) fwnode = dev_fwnode(&indio_dev->dev); - else + /* The default dummy IIO device has no parent */ + else if (indio_dev->dev.parent) fwnode = dev_fwnode(indio_dev->dev.parent); device_set_node(&indio_dev->dev, fwnode);
Commit 813665564b3d ("iio: core: Convert to use firmware node handle instead of OF node") switched the kind of nodes to use for label retrieval in device registration. Probably an unwanted change in that commit was that if the device has no parent then NULL pointer is accessed. This is what happens in the stock IIO dummy driver when a new entry is created in configfs: # mkdir /sys/kernel/config/iio/devices/dummy/foo BUG: kernel NULL pointer dereference, address: ... ... Call Trace: __iio_device_register iio_dummy_probe Since there seems to be no reason to make a parent device of an IIO dummy device mandatory, let’s prevent the invalid memory access in __iio_device_register when the parent device is NULL. With this change, the IIO dummy driver works fine with configfs. Fixes: 813665564b3d ("iio: core: Convert to use firmware node handle instead of OF node") Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Milan Zamazal <mzamazal@redhat.com> --- Changes in v3: - The call trace in the commit message reduced to the minimum lines needed to explain the problem. Changes in v2: - Added a source comment about the dummy IIO device. - Adjusted the backtrace cited in the commit message a bit. - Replaced `... != NULL' condition with `...'. - Dropped the unnecessary `fwnode != NULL' check (the involved calls do the right thing when the argument is NULL). --- drivers/iio/industrialio-core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)