[PATCH] i3c: master: Fix device_register() error path

[PATCH] i3c: master: Fix device_register() error path

[Adrian Hunter]

When device_register() fails in i3c_master_register_new_i3c_devs(),
put_device() is called to drop the reference taken by
device_register().  That drops the last reference, so the device's
release callback i3c_device_release() runs and frees the i3c_device.

Two problems follow from that:

i3c_device_release() does WARN_ON(i3cdev->desc), so it warns because
desc->dev->desc still points back at the descriptor.  Clear it before
calling put_device().

After put_device() frees the i3c_device, desc->dev is left pointing at
freed memory, so clear desc->dev as well.  That prevents, for example,
i3c_master_unregister_i3c_devs() seeing desc->dev as non-NULL and
dereferencing it.

Reported-by: sashiko-bot@kernel.org
Link: https://lore.kernel.org/linux-i3c/20260701203053.8F3971F000E9@smtp.kernel.org/
Fixes: cab63f6488761 ("i3c: Fix potential refcount leak in i3c_master_register_new_i3c_devs")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/i3c/master.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 979457e635bd..7254b13fe4f0 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -1942,7 +1942,9 @@ i3c_master_register_new_i3c_devs(struct i3c_master_controller *master)
 		if (ret) {
 			dev_err(&master->dev,
 				"Failed to add I3C device (err = %d)\n", ret);
+			desc->dev->desc = NULL;
 			put_device(&desc->dev->dev);
+			desc->dev = NULL;
 		}
 	}
 }
-- 
2.53.0

Re: [PATCH] i3c: master: Fix device_register() error path

[Frank Li]

On Thu, Jul 02, 2026 at 09:36:44PM +0300, Adrian Hunter wrote:
> When device_register() fails in i3c_master_register_new_i3c_devs(),
> put_device() is called to drop the reference taken by
> device_register().  That drops the last reference, so the device's
> release callback i3c_device_release() runs and frees the i3c_device.
>
> Two problems follow from that:
>
> i3c_device_release() does WARN_ON(i3cdev->desc), so it warns because
> desc->dev->desc still points back at the descriptor.  Clear it before
> calling put_device().
>
> After put_device() frees the i3c_device, desc->dev is left pointing at
> freed memory, so clear desc->dev as well.  That prevents, for example,
> i3c_master_unregister_i3c_devs() seeing desc->dev as non-NULL and
> dereferencing it.
>
> Reported-by: sashiko-bot@kernel.org
> Link: https://lore.kernel.org/linux-i3c/20260701203053.8F3971F000E9@smtp.kernel.org/
> Fixes: cab63f6488761 ("i3c: Fix potential refcount leak in i3c_master_register_new_i3c_devs")
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>  drivers/i3c/master.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index 979457e635bd..7254b13fe4f0 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -1942,7 +1942,9 @@ i3c_master_register_new_i3c_devs(struct i3c_master_controller *master)
>  		if (ret) {
>  			dev_err(&master->dev,
>  				"Failed to add I3C device (err = %d)\n", ret);
> +			desc->dev->desc = NULL;
>  			put_device(&desc->dev->dev);
> +			desc->dev = NULL;
>  		}
>  	}
>  }
> --
> 2.53.0
>