4.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Yonghong Song <yhs@xxxxxx>
[ 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@xxxxxxxxxx>
Reported-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Tested-by: Mathieu Malaterre <malat@xxxxxxxxxx>
Signed-off-by: Yonghong Song <yhs@xxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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)