Re: [PATCH] bpf: check NULL for sk_to_full_sk()

[Eric Dumazet]

On 05/21/2018 12:55 AM, YueHaibing wrote:
> like commit df39a9f106d5 ("bpf: check NULL for sk_to_full_sk() return value"),
> we should check sk_to_full_sk return value against NULL.
> 
> Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
> ---
>  include/linux/bpf-cgroup.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
> index 30d15e6..fd3fbeb 100644
> --- a/include/linux/bpf-cgroup.h
> +++ b/include/linux/bpf-cgroup.h
> @@ -91,7 +91,7 @@ int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
>  	int __ret = 0;							       \
>  	if (cgroup_bpf_enabled && sk && sk == skb->sk) {		       \
>  		typeof(sk) __sk = sk_to_full_sk(sk);			       \
> -		if (sk_fullsock(__sk))					       \
> +		if (__sk && sk_fullsock(__sk))				       \
>  			__ret = __cgroup_bpf_run_filter_skb(__sk, skb,	       \
>  						      BPF_CGROUP_INET_EGRESS); \
>  	}								       \
> 

Why is this needed ???