* [PATCH 1/1] l2tp: fix possible use-after-free
@ 2022-06-10 5:16 Xiaohui Zhang
2022-06-14 8:06 ` Paolo Abeni
0 siblings, 1 reply; 3+ messages in thread
From: Xiaohui Zhang @ 2022-06-10 5:16 UTC (permalink / raw)
To: Xiaohui Zhang, David S . Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, Xiyu Yang, Xin Tan, Xin Xiong, Tom Parkin, netdev,
linux-kernel
Similar to the handling of l2tp_tunnel_get in commit a622b40035d1
("l2ip: fix possible use-after-free"), we thought a patch might
be needed here as well.
Before taking a refcount on a rcu protected structure,
we need to make sure the refcount is not zero.
Signed-off-by: Xiaohui Zhang <xiaohuizhang@ruc.edu.cn>
---
net/l2tp/l2tp_core.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 7499c51b1850..96e8966f900d 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -252,8 +252,8 @@ struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
rcu_read_lock_bh();
hlist_for_each_entry_rcu(session, session_list, hlist)
- if (session->session_id == session_id) {
- l2tp_session_inc_refcount(session);
+ if (session->session_id == session_id &&
+ refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
@@ -273,8 +273,8 @@ struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id)
rcu_read_lock_bh();
hlist_for_each_entry_rcu(session, session_list, global_hlist)
- if (session->session_id == session_id) {
- l2tp_session_inc_refcount(session);
+ if (session->session_id == session_id &&
+ refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
@@ -294,8 +294,8 @@ struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth)
rcu_read_lock_bh();
for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) {
- if (++count > nth) {
- l2tp_session_inc_refcount(session);
+ if (++count > nth &&
+ refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
}
@@ -321,8 +321,8 @@ struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
rcu_read_lock_bh();
for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) {
- if (!strcmp(session->ifname, ifname)) {
- l2tp_session_inc_refcount(session);
+ if (!strcmp(session->ifname, ifname) &&
+ refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 1/1] l2tp: fix possible use-after-free
2022-06-10 5:16 [PATCH 1/1] l2tp: fix possible use-after-free Xiaohui Zhang
@ 2022-06-14 8:06 ` Paolo Abeni
0 siblings, 0 replies; 3+ messages in thread
From: Paolo Abeni @ 2022-06-14 8:06 UTC (permalink / raw)
To: Xiaohui Zhang, David S . Miller, Eric Dumazet, Jakub Kicinski,
Xiyu Yang, Xin Tan, Xin Xiong, Tom Parkin, netdev, linux-kernel
On Fri, 2022-06-10 at 13:16 +0800, Xiaohui Zhang wrote:
> Similar to the handling of l2tp_tunnel_get in commit a622b40035d1
> ("l2ip: fix possible use-after-free"), we thought a patch might
> be needed here as well.
>
> Before taking a refcount on a rcu protected structure,
> we need to make sure the refcount is not zero.
>
> Signed-off-by: Xiaohui Zhang <xiaohuizhang@ruc.edu.cn>
I'm sorry for the late, trivial feedback, but we need a Fixes: tag
here. Since you need to repost, please insert the target tree
explicitly into the email subj.
Thanks!
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH 1/1] l2tp: fix possible use-after-free
@ 2022-06-05 11:35 Xiaohui Zhang
0 siblings, 0 replies; 3+ messages in thread
From: Xiaohui Zhang @ 2022-06-05 11:35 UTC (permalink / raw)
To: Xiaohui Zhang, David S . Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, netdev, linux-kernel
From: xiaohuizhang98 <ruc_zhangxiaohui@163.com>
We detected a suspected bug with our code clone detection tool.
Similar to the handling of l2tp_tunnel_get in commit a622b40035d1
("l2ip: fix possible use-after-free"), we thought a patch might
be needed here as well.
Before taking a refcount on a rcu protected structure,
we need to make sure the refcount is not zero.
Signed-off-by: xiaohuizhang98 <ruc_zhangxiaohui@163.com>
---
net/l2tp/l2tp_core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 7499c51b1850..b759fbd09b65 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -252,8 +252,8 @@ struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
rcu_read_lock_bh();
hlist_for_each_entry_rcu(session, session_list, hlist)
- if (session->session_id == session_id) {
- l2tp_session_inc_refcount(session);
+ if (session->session_id == session_id &&
+ refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
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