Commit 9a3efb6b authored Feb 13, 2018 by Yonghong Song Committed by Alexei Starovoitov Feb 13, 2018

bpf: fix memory leak in lpm_trie map_free callback function



There is a memory leak happening in lpm_trie map_free callback
function trie_free. The trie structure itself does not get freed.

Also, trie_free function did not do synchronize_rcu before freeing
various data structures. This is incorrect as some rcu_read_lock
region(s) for lookup, update, delete or get_next_key may not complete yet.
The fix is to add synchronize_rcu in the beginning of trie_free.
The useless spin_lock is removed from this function as well.

Fixes: b95a5c4d ("bpf: add a longest prefix match trie map implementation")
Reported-by: Mathieu Malaterre <malat@debian.org>
Reported-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent d4014d8c

kernel/bpf/lpm_trie.c

+7 −4

Original line number	Diff line number	Diff line
		@@ -555,7 +555,10 @@ static void trie_free(struct bpf_map *map)
		struct lpm_trie_node __rcu **slot;
		struct lpm_trie_node *node;

		raw_spin_lock(&trie->lock);
		/* Wait for outstanding programs to complete
		* update/lookup/delete/get_next_key and free the trie.
		*/
		synchronize_rcu();

		/* Always start at the root and walk down to a node that has no
		* children. Then free that node, nullify its reference in the parent
		@@ -569,7 +572,7 @@ static void trie_free(struct bpf_map *map)
		node = rcu_dereference_protected(*slot,
		lockdep_is_held(&trie->lock));
		if (!node)
		goto unlock;
		goto out;

		if (rcu_access_pointer(node->child[0])) {
		slot = &node->child[0];
		@@ -587,8 +590,8 @@ static void trie_free(struct bpf_map *map)
		}
		}

		unlock:
		raw_spin_unlock(&trie->lock);
		out:
		kfree(trie);
		}

		static int trie_get_next_key(struct bpf_map map, void _key, void *_next_key)