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bpf: fix memory leak in lpm_trie map_free callback function

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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: b95a5c4db0 ("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>
This commit is contained in:
Yonghong Song 2018-02-13 19:00:21 -08:00 committed by Alexei Starovoitov
parent d4014d8cc6
commit 9a3efb6b66
1 changed files with 7 additions and 4 deletions
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11
kernel/bpf/lpm_trie.c
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@ -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)