Re: [PATCH] net: Avoid calling WARN_ON() on -ENOMEM in __dev_change_net_namespace()

[Breno Leitao]

Hello Ivan,

On Fri, Mar 28, 2025 at 04:12:57AM +0300, Ivan Abramov wrote:
> It's pointless to call WARN_ON() in case of an allocation failure in
> device_rename(), since it only leads to useless splats caused by deliberate
> fault injections, so avoid it.
> 
> Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
> 
> Fixes: 8b41d1887db7 ("[NET]: Fix running without sysfs")
> Signed-off-by: Ivan Abramov <i.abramov@xxxxxxxxxxxxxxxxx>
> ---
>  net/core/dev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 2f7f5fd9ffec..14726cc8796b 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -12102,7 +12102,7 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net,
>  	dev_set_uevent_suppress(&dev->dev, 1);
>  	err = device_rename(&dev->dev, dev->name);
>  	dev_set_uevent_suppress(&dev->dev, 0);
> -	WARN_ON(err);
> +	WARN_ON(err && err != -ENOMEM);


I am curious if we shouldn't skip the rest of that function if
device_rename failed. Something as:

	if (WARN_ON(err && err != -ENOMEM))
		goto out;