Re: [bug report] of: overlay: rework overlay apply and remove kfree()s

[Frank Rowand <frowand.list@gmail.com>]

On 4/27/22 02:44, Dan Carpenter wrote:
> Hello Frank Rowand,
> 
> The patch 067c098766c6: "of: overlay: rework overlay apply and remove
> kfree()s" from Apr 20, 2022, leads to the following Smatch static
> checker warning:
> 
> 	drivers/of/overlay.c:180 overlay_notify()
> 	error: buffer overflow 'of_overlay_action_name' 4 <= 4
> 
> drivers/of/overlay.c
>    155  static char *of_overlay_action_name[] = {
> 
> We need to add a "init" string at the start of this array.
> 
>    156          "pre-apply",
>    157          "post-apply",
>    158          "pre-remove",
>    159          "post-remove",
>    160  };
>    161  
>     162 static int overlay_notify(struct overlay_changeset *ovcs,
>     163                 enum of_overlay_notify_action action)
>     164 {
>     165         struct of_overlay_notify_data nd;
>     166         int i, ret;
>     167 
>     168         ovcs->notify_state = action;
>     169 
>     170         for (i = 0; i < ovcs->count; i++) {
>     171                 struct fragment *fragment = &ovcs->fragments[i];
>     172 
>     173                 nd.target = fragment->target;
>     174                 nd.overlay = fragment->overlay;
>     175 
>     176                 ret = blocking_notifier_call_chain(&overlay_notify_chain,
>     177                                                    action, &nd);
>     178                 if (notifier_to_errno(ret)) {
>     179                         ret = notifier_to_errno(ret);
> --> 180                         pr_err("overlay changeset %s notifier error %d, target: %pOF\n",
>     181                                of_overlay_action_name[action], ret, nd.target);
>                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> These are all shifted and so post remove is out of bounds.
> 
>     182                         return ret;
>     183                 }
>     184         }
>     185 
>     186         return 0;
>     187 }
> 
> regards,
> dan carpenter

Thanks for the bug report!

I'm working on a patch to fix (easy) and a patch to add some unittest tests
to verify the overlay notifiers (a little bit more time consuming).

-Frank