Re: [PATCH v4 1/3] bpf: add a longest prefix match trie map implementation

[Daniel Mack <daniel@zonque.org>]

On 01/23/2017 05:39 PM, Daniel Borkmann wrote:
> On 01/21/2017 05:26 PM, Daniel Mack wrote:
> [...]
>> +/* Called from syscall or from eBPF program */
>> +static int trie_update_elem(struct bpf_map *map,
>> +			    void *_key, void *value, u64 flags)
>> +{
>> +	struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
>> +	struct lpm_trie_node *node, *im_node, *new_node = NULL;
> 
> im_node is uninitialized here ...
> 
>> +	struct lpm_trie_node __rcu **slot;
>> +	struct bpf_lpm_trie_key *key = _key;
>> +	unsigned long irq_flags;
>> +	unsigned int next_bit;
>> +	size_t matchlen = 0;
>> +	int ret = 0;
>> +
>> +	if (unlikely(flags > BPF_EXIST))
>> +		return -EINVAL;
>> +
>> +	if (key->prefixlen > trie->max_prefixlen)
>> +		return -EINVAL;
>> +
>> +	raw_spin_lock_irqsave(&trie->lock, irq_flags);
>> +
>> +	/* Allocate and fill a new node */
>> +
>> +	if (trie->n_entries == trie->map.max_entries) {
>> +		ret = -ENOSPC;
>> +		goto out;
> 
> ... and here we go to out path with ret as non-zero ...
> 
>> +	}
>> +
>> +	new_node = lpm_trie_node_alloc(trie, value);
>> +	if (!new_node) {
>> +		ret = -ENOMEM;
>> +		goto out;
>> +	}
> [...]
>> +
>> +out:
>> +	if (ret) {
>> +		if (new_node)
>> +			trie->n_entries--;
>> +
>> +		kfree(new_node);
>> +		kfree(im_node);
> 
> ... which does kfree() in im_node here.

Oops. Nice catch! gcc was too stupid to recognize that :)

Thanks, I'll repost a v5 with Alexei's Acked-by later today.


Daniel