Re: [PATCH net] net: fix NULL dereference in skb realloc fault injection devname filter

[Breno Leitao]

> --- a/net/core/skb_fault_injection.c
> +++ b/net/core/skb_fault_injection.c
> @@ -19,8 +19,8 @@ static bool should_fail_net_realloc_skb(struct sk_buff *skb)
>  	struct net_device *net = skb->dev;
>  
>  	if (skb_realloc.filtered &&
> -	    strncmp(net->name, skb_realloc.devname, IFNAMSIZ))
> -		/* device name filter set, but names do not match */
> +	    (!net || strncmp(net->name, skb_realloc.devname, IFNAMSIZ)))
> +		/* device name filter set, but no device or names do not match */
>  		return false;
>  
>  	if (!should_fail(&skb_realloc.attr, 1))

I think something like this untested approach reads better:

diff --git a/net/core/skb_fault_injection.c b/net/core/skb_fault_injection.c
index 4235db6bdfad55..63a397f761133c 100644
--- a/net/core/skb_fault_injection.c
+++ b/net/core/skb_fault_injection.c
@@ -18,6 +18,9 @@ static bool should_fail_net_realloc_skb(struct sk_buff *skb)
 {
        struct net_device *net = skb->dev;

+       if (!net)
+               return false;
+
        if (skb_realloc.filtered &&
            strncmp(net->name, skb_realloc.devname, IFNAMSIZ))
                /* device name filter set, but names do not match */