2021-04-22 20:27:36

by Tomasz Duszynski

Subject: [PATCH] iio: core: fix ioctl handlers removal

Currently ioctl handlers are removed twice. For the first time during
iio_device_unregister() then later on inside
iio_device_unregister_eventset() and iio_buffers_free_sysfs_and_mask().
Double free leads to kernel panic.

Fix this by not touching ioctl handlers list directly but rather
letting code responsible for registration call the matching cleanup
routine itself.

Signed-off-by: Tomasz Duszynski <[email protected]>
---
drivers/iio/industrialio-core.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index d92c58a94fe4..98944cfc7331 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1939,9 +1939,6 @@ void iio_device_unregister(struct iio_dev *indio_dev)

indio_dev->info = NULL;

- list_for_each_entry_safe(h, t, &iio_dev_opaque->ioctl_handlers, entry)
- list_del(&h->entry);
-
iio_device_wakeup_eventset(indio_dev);
iio_buffer_wakeup_poll(indio_dev);

--
2.31.1

2021-04-23 07:18:41

by Alexandru Ardelean

Subject: Re: [PATCH] iio: core: fix ioctl handlers removal

On Thu, Apr 22, 2021 at 11:26 PM Tomasz Duszynski
<[email protected]> wrote:
>
> Currently ioctl handlers are removed twice. For the first time during
> iio_device_unregister() then later on inside
> iio_device_unregister_eventset() and iio_buffers_free_sysfs_and_mask().
> Double free leads to kernel panic.
>
> Fix this by not touching ioctl handlers list directly but rather
> letting code responsible for registration call the matching cleanup
> routine itself.
>

This change is missing this tag:

Fixes: 8dedcc3eee3ac ("iio: core: centralize ioctl() calls to the main chardev")

With that tag added:
Acked-by: Alexandru Ardelean <[email protected]>

Apologies for the breakage.
Also, I wasn't sure if Jonathan or anyone else wanted to do this change.

Thanks for the patch
Alex

> Signed-off-by: Tomasz Duszynski <[email protected]>
> ---
> drivers/iio/industrialio-core.c | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index d92c58a94fe4..98944cfc7331 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -1939,9 +1939,6 @@ void iio_device_unregister(struct iio_dev *indio_dev)
>
> indio_dev->info = NULL;
>
> - list_for_each_entry_safe(h, t, &iio_dev_opaque->ioctl_handlers, entry)
> - list_del(&h->entry);
> -
> iio_device_wakeup_eventset(indio_dev);
> iio_buffer_wakeup_poll(indio_dev);
>
> --
> 2.31.1
>

2021-04-23 08:05:13

by Tomasz Duszynski

Subject: Re: [PATCH] iio: core: fix ioctl handlers removal

On Fri, Apr 23, 2021 at 10:17:42AM +0300, Alexandru Ardelean wrote:
> On Thu, Apr 22, 2021 at 11:26 PM Tomasz Duszynski
> <[email protected]> wrote:
> >
> > Currently ioctl handlers are removed twice. For the first time during
> > iio_device_unregister() then later on inside
> > iio_device_unregister_eventset() and iio_buffers_free_sysfs_and_mask().
> > Double free leads to kernel panic.
> >
> > Fix this by not touching ioctl handlers list directly but rather
> > letting code responsible for registration call the matching cleanup
> > routine itself.
> >
>
> This change is missing this tag:
>
> Fixes: 8dedcc3eee3ac ("iio: core: centralize ioctl() calls to the main chardev")
>
> With that tag added:
> Acked-by: Alexandru Ardelean <[email protected]>
>
> Apologies for the breakage.

No worries. Will append you ack to v2 then.

> Also, I wasn't sure if Jonathan or anyone else wanted to do this change.
>
> Thanks for the patch
> Alex
>
> > Signed-off-by: Tomasz Duszynski <[email protected]>
> > ---
> > drivers/iio/industrialio-core.c | 3 ---
> > 1 file changed, 3 deletions(-)
> >
> > diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> > index d92c58a94fe4..98944cfc7331 100644
> > --- a/drivers/iio/industrialio-core.c
> > +++ b/drivers/iio/industrialio-core.c
> > @@ -1939,9 +1939,6 @@ void iio_device_unregister(struct iio_dev *indio_dev)
> >
> > indio_dev->info = NULL;
> >
> > - list_for_each_entry_safe(h, t, &iio_dev_opaque->ioctl_handlers, entry)
> > - list_del(&h->entry);
> > -
> > iio_device_wakeup_eventset(indio_dev);
> > iio_buffer_wakeup_poll(indio_dev);
> >
> > --
> > 2.31.1
> >