[v3,1/4] usb: typec: ucsi: Fix null pointer dereference in trace

From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>

ucsi_register_altmode checks IS_ERR on returned pointer and treats
NULL as valid. When CONFIG_TYPEC_DP_ALTMODE is not enabled
ucsi_register_displayport returns NULL which causese a NULL pointer
dereference in trace. Rather than return NULL, call
typec_port_register_altmode to register DisplayPort alternate mode
as a non-controllable mode when CONFIG_TYPEC_DP_ALTMODE is not enabled.

Reviewed-by: Jameson Thies <jthies@google.com>
Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
---
Changes in V3:
- Returns typec_port_register_altmode call from
ucsi_register_displayport when CONFIG_TYPEC_DP_ALTMODE is not enabled.

Changes in V2:
- Checks for error response from ucsi_register_displayport when
registering DisplayPort alternate mode.

 drivers/usb/typec/ucsi/ucsi.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

>                                      … which causese a NULL pointer
…

I hope that a typo will be avoided in the change description for the final commit.


…
> ---
> Changes in V3:
…

How do you think about to mention also adjustments for the commit message here?

Regards,
Markus

On Sat, May 04, 2024 at 07:12:49AM +0200, Markus Elfring wrote:
> > I don't think it is necessary to mention changes to the commit message
> > in the section below the commit message.
> 
> Did you notice that other contributors occasionally share hints about
> adjustments for parts of commit messages?
> Will further information presentation become better supported?

Hi,

This is the semi-friendly patch-bot of Greg Kroah-Hartman.

Markus, you seem to have sent a nonsensical or otherwise pointless
review comment to a patch submission on a Linux kernel developer mailing
list.  I strongly suggest that you not do this anymore.  Please do not
bother developers who are actively working to produce patches and
features with comments that, in the end, are a waste of time.

Patch submitter, please ignore Markus's suggestion; you do not need to
follow it at all.  The person/bot/AI that sent it is being ignored by
almost all Linux kernel maintainers for having a persistent pattern of
behavior of producing distracting and pointless commentary, and
inability to adapt to feedback.  Please feel free to also ignore emails
from them.

thanks,

greg k-h's patch email bot

On Fri, May 03, 2024 at 12:39:17AM +0000, Jameson Thies wrote:
> From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> 
> ucsi_register_altmode checks IS_ERR on returned pointer and treats
> NULL as valid. When CONFIG_TYPEC_DP_ALTMODE is not enabled
> ucsi_register_displayport returns NULL which causese a NULL pointer
> dereference in trace. Rather than return NULL, call
> typec_port_register_altmode to register DisplayPort alternate mode
> as a non-controllable mode when CONFIG_TYPEC_DP_ALTMODE is not enabled.
> 
> Reviewed-by: Jameson Thies <jthies@google.com>
> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>

You delivered the patch, so you should have used SoB instead of
Reviewed-by tag:
https://docs.kernel.org/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
> Changes in V3:
> - Returns typec_port_register_altmode call from
> ucsi_register_displayport when CONFIG_TYPEC_DP_ALTMODE is not enabled.
> 
> Changes in V2:
> - Checks for error response from ucsi_register_displayport when
> registering DisplayPort alternate mode.
> 
>  drivers/usb/typec/ucsi/ucsi.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
> index c4d103db9d0f8..f66224a270bc6 100644
> --- a/drivers/usb/typec/ucsi/ucsi.h
> +++ b/drivers/usb/typec/ucsi/ucsi.h
> @@ -496,7 +496,7 @@ ucsi_register_displayport(struct ucsi_connector *con,
>  			  bool override, int offset,
>  			  struct typec_altmode_desc *desc)
>  {
> -	return NULL;
> +	return typec_port_register_altmode(con->port, desc);
>  }
>  
>  static inline void
> -- 
> 2.45.0.rc1.225.g2a3ae87e7f-goog

On Mon, May 06, 2024 at 01:03:12PM +0300, Heikki Krogerus wrote:
> On Fri, May 03, 2024 at 12:39:17AM +0000, Jameson Thies wrote:
> > From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> > 
> > ucsi_register_altmode checks IS_ERR on returned pointer and treats
> > NULL as valid. When CONFIG_TYPEC_DP_ALTMODE is not enabled
> > ucsi_register_displayport returns NULL which causese a NULL pointer
> > dereference in trace. Rather than return NULL, call
> > typec_port_register_altmode to register DisplayPort alternate mode
> > as a non-controllable mode when CONFIG_TYPEC_DP_ALTMODE is not enabled.
> > 
> > Reviewed-by: Jameson Thies <jthies@google.com>
> > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> 
> You delivered the patch, so you should have used SoB instead of
> Reviewed-by tag:
> https://docs.kernel.org/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by

Not "should", that would be "must". I can't take it like this, sorry.

greg k-h

Thank you for the feedback, I'll post a v4 series fixing these issues.

Thanks,
Jameson