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 <[email protected]>
Reported-by: Alexei Starovoitov <[email protected]>
Tested-by: Mathieu Malaterre <[email protected]>
Signed-off-by: Yonghong Song <[email protected]>
---
kernel/bpf/lpm_trie.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c
index 7b469d1..9b41ea4 100644
--- a/kernel/bpf/lpm_trie.c
+++ b/kernel/bpf/lpm_trie.c
@@ -555,7 +555,12 @@ static void trie_free(struct bpf_map *map)
struct lpm_trie_node __rcu **slot;
struct lpm_trie_node *node;
- raw_spin_lock(&trie->lock);
+ /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
+ * so the programs (can be more than one that used this map) were
+ * disconnected from events. 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
@@ -588,7 +593,7 @@ static void trie_free(struct bpf_map *map)
}
unlock:
- raw_spin_unlock(&trie->lock);
+ kfree(trie);
}
static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
--
2.9.5
