[PATCH] netlink: fix memory leak

From: Shaochun Chen
Date: Sat Jul 21 2018 - 22:51:35 EST


when netlink_dump start failed, netlink_callback will not be called,
and the memory which pointed by control->data will leak. so if netlink_dump
start fail, call control->done to free the memory.

Signed-off-by: Shaochun Chen <cscnull@xxxxxxxxx>
---
include/linux/netlink.h | 10 ++++++++++
net/netfilter/nf_tables_api.c | 4 +++-
net/netlink/af_netlink.c | 4 ++++
3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index f3075d6c7e82..9d6b3edc5a5b 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -214,6 +214,16 @@ static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
return __netlink_dump_start(ssk, skb, nlh, control);
}

+static inline void netlink_dump_start_fail(struct netlink_dump_control *control)
+{
+ struct netlink_callback cb = {
+ .data = control->data,
+ };
+
+ if (control->done)
+ control->done(&cb);
+}
+
struct netlink_tap {
struct net_device *dev;
struct module *module;
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 896d4a36081d..dc30a329f785 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -588,8 +588,10 @@ static int nft_netlink_dump_start_rcu(struct sock *nlsk, struct sk_buff *skb,
{
int err;

- if (!try_module_get(THIS_MODULE))
+ if (!try_module_get(THIS_MODULE)) {
+ netlink_dump_start_fail(c);
return -EINVAL;
+ }

rcu_read_unlock();
err = netlink_dump_start(nlsk, skb, nlh, c);
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 393573a99a5a..7b85176cf9bb 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2275,6 +2275,7 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
struct netlink_callback *cb;
struct sock *sk;
struct netlink_sock *nlk;
+ bool cb_running = false;
int ret;

refcount_inc(&skb->users);
@@ -2317,6 +2318,7 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,

nlk->cb_running = true;
nlk->dump_done_errno = INT_MAX;
+ cb_running = true;

mutex_unlock(nlk->cb_mutex);

@@ -2339,6 +2341,8 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
mutex_unlock(nlk->cb_mutex);
error_free:
kfree_skb(skb);
+ if (cb_running)
+ netlink_dump_start_fail(control);
return ret;
}
EXPORT_SYMBOL(__netlink_dump_start);
--
2.17.1