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Subject[PATCH 4.14 2/9] bpf: fix memory leak in lpm_trie map_free callback function
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

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
@@ -470,7 +470,10 @@ 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
@@ -484,7 +487,7 @@ 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];
@@ -502,8 +505,8 @@ 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)

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