[congwang:sch_bpf 2/4] net/core/skb_map.c:175 skb_map_get_next_key() error: we previously assumed 'key' could be null (see line 170)

From: Dan Carpenter
Date: Mon May 23 2022 - 09:23:08 EST

tree: https://github.com/congwang/linux.git sch_bpf
head: 6ffa225aaaaa22848f4629fc911a682553f17770
commit: 87784a11f90e7582ee664b531af17f7ca6ce2b62 [2/4] bpf: introduce skb map
config: i386-randconfig-m021 (https://download.01.org/0day-ci/archive/20220522/202205221325.tXVMMrOx-lkp@xxxxxxxxx/config)
compiler: gcc-11 (Debian 11.3.0-1) 11.3.0

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

smatch warnings:
net/core/skb_map.c:175 skb_map_get_next_key() error: we previously assumed 'key' could be null (see line 170)

vim +/key +175 net/core/skb_map.c

87784a11f90e75 Cong Wang 2020-11-08 164 static int skb_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
87784a11f90e75 Cong Wang 2020-11-08 165 {
87784a11f90e75 Cong Wang 2020-11-08 166 struct bpf_skb_map *rb = bpf_skb_map(map);
87784a11f90e75 Cong Wang 2020-11-08 167 struct sk_buff *skb;
87784a11f90e75 Cong Wang 2020-11-08 168 u64 rank;
87784a11f90e75 Cong Wang 2020-11-08 169
87784a11f90e75 Cong Wang 2020-11-08 @170 if (!key) {

If key is NULL

87784a11f90e75 Cong Wang 2020-11-08 171 skb = skb_rb_first(&rb->root);
87784a11f90e75 Cong Wang 2020-11-08 172 if (!skb)
87784a11f90e75 Cong Wang 2020-11-08 173 return -ENOENT;
87784a11f90e75 Cong Wang 2020-11-08 174 }
87784a11f90e75 Cong Wang 2020-11-08 @175 rank = *(u64 *) key;

Then we are toasted

87784a11f90e75 Cong Wang 2020-11-08 176 skb = skb_rb_find(&rb->root, rank);
87784a11f90e75 Cong Wang 2020-11-08 177 if (!skb)
87784a11f90e75 Cong Wang 2020-11-08 178 return -ENOENT;
87784a11f90e75 Cong Wang 2020-11-08 179 skb = skb_rb_next(skb);
87784a11f90e75 Cong Wang 2020-11-08 180 if (!skb)
87784a11f90e75 Cong Wang 2020-11-08 181 return 0;
87784a11f90e75 Cong Wang 2020-11-08 182 *(u64 *) next_key = skb_map_cb(skb)->rank;
87784a11f90e75 Cong Wang 2020-11-08 183 return 0;
87784a11f90e75 Cong Wang 2020-11-08 184 }

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