Re: [PATCH v2 1/4] usb: typec: ucsi: Fix null deref in trace

[Dan Carpenter]

On Wed, Apr 24, 2024 at 01:48:18AM +0000, Jameson Thies wrote:
> From: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
> 
> ucsi_register_altmode checks IS_ERR on returned pointer and treats
> NULL as valid. This results in a null deref when
> trace_ucsi_register_altmode is called. Return an error from
> ucsi_register_displayport when it is not supported and register the
> altmode with typec_port_register_altmode.
> 
> Reviewed-by: Jameson Thies <jthies@xxxxxxxxxx>
> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>

This is not the correct way to fix this.  The normal thing to do would
be to add NULL checks.

https://staticthinking.wordpress.com/2022/08/01/mixing-error-pointers-and-null/'

regards,
dan carpenter