4.15-stable review patch. If anyone has any objections, please let me know.
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From: Yonghong Song yhs@fb.com
[ upstream commit 9a3efb6b661f71d5675369ace9257833f0e78ef3 ]
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: b95a5c4db09b ("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 Signed-off-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/bpf/lpm_trie.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
--- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -560,7 +560,10 @@ static void trie_free(struct bpf_map *ma 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 @@ -574,7 +577,7 @@ static void trie_free(struct bpf_map *ma 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]; @@ -592,8 +595,8 @@ static void trie_free(struct bpf_map *ma } }
-unlock: - raw_spin_unlock(&trie->lock); +out: + kfree(trie); }
static int trie_get_next_key(struct bpf_map *map, void *key, void *next_key)