[PATCH] bpf: check NULL for sk_to_full_sk()

[YueHaibing]

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 <yuehaib...@huawei.com>
---
 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); \
        }                                                                      \
-- 
2.7.0