Re: [PATCH 4/4] nfc: Avoid endless loops caused by repeated llcp_sock_connect()(Internet mail)

2021-03-04 Thread Xiaoming Ni 

On 2021/3/3 17:28, kiyin(尹亮) wrote:

Hi xiaoming,
   the path can only fix the endless loop problem. it can't fix the meaningless 
llcp_sock->service_name problem.
   if we set llcp_sock->service_name to meaningless string, the connect will be failed. and 
sk->sk_state will not be LLCP_CONNECTED. then we can call llcp_sock_connect() many times. that 
leaks everything: llcp_sock->dev, llcp_sock->local, llcp_sock->ssap, 
llcp_sock->service_name...


I didn't find the code to modify sk->sk_state after a connect failure. 
Can you provide guidance?


Based on my understanding of the current code:
After llcp_sock_connect() is invoked using the meaningless service_name 
as the parameter, sk->sk_state is set to LLCP_CONNECTING. After that, no 
corresponding service responds to the request because the service_name 
is meaningless, the value of sk->sk_state remains unchanged.
Therefore, when llcp_sock_connect() is invoked again, resources such as 
llcp_sock->service_name are not repeatedly applied because sk_state is 
set to LLCP_CONNECTING.


In this way, the repeated invoking of llcp_sock_connect() does not 
repeatedly leak resources.


Thanks
Xiaoming Ni





-Original Message-
From: Xiaoming Ni [mailto:nixiaom...@huawei.com]
Sent: Wednesday, March 3, 2021 2:17 PM
To: linux-kernel@vger.kernel.org; kiyin(尹亮) ;
sta...@vger.kernel.org; gre...@linuxfoundation.org; sa...@linux.intel.com;
linvi...@tuxdriver.com; da...@davemloft.net; k...@kernel.org;
m...@pengutronix.de; ste...@datenfreihafen.org;
matthieu.bae...@tessares.net; net...@vger.kernel.org
Cc: nixiaom...@huawei.com; wang...@huawei.com; xiaoqi...@huawei.com
Subject: [PATCH 4/4] nfc: Avoid endless loops caused by repeated
llcp_sock_connect()(Internet mail)

When sock_wait_state() returns -EINPROGRESS, "sk->sk_state" is
LLCP_CONNECTING. In this case, llcp_sock_connect() is repeatedly invoked,
  nfc_llcp_sock_link() will add sk to local->connecting_sockets twice.
  sk->sk_node->next will point to itself, that will make an endless loop  and
hang-up the system.
To fix it, check whether sk->sk_state is LLCP_CONNECTING in
  llcp_sock_connect() to avoid repeated invoking.

fix CVE-2020-25673
Fixes: b4011239a08e ("NFC: llcp: Fix non blocking sockets connections")
Reported-by: "kiyin(尹亮)" 
Link: https://www.openwall.com/lists/oss-security/2020/11/01/1
Cc:  #v3.11
Signed-off-by: Xiaoming Ni 
---
  net/nfc/llcp_sock.c | 4 
  1 file changed, 4 insertions(+)

diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c index
59172614b249..a3b46f03 100644
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -673,6 +673,10 @@ static int llcp_sock_connect(struct socket *sock,
struct sockaddr *_addr,
ret = -EISCONN;
goto error;
}
+   if (sk->sk_state == LLCP_CONNECTING) {
+   ret = -EINPROGRESS;
+   goto error;
+   }

dev = nfc_get_device(addr->dev_idx);
if (dev == NULL) {
--
2.27.0

RE: [PATCH 4/4] nfc: Avoid endless loops caused by repeated llcp_sock_connect()(Internet mail)

2021-03-03 Thread 尹亮 
Hi xiaoming,
  the path can only fix the endless loop problem. it can't fix the meaningless 
llcp_sock->service_name problem.
  if we set llcp_sock->service_name to meaningless string, the connect will be 
failed. and sk->sk_state will not be LLCP_CONNECTED. then we can call 
llcp_sock_connect() many times. that leaks everything: llcp_sock->dev, 
llcp_sock->local, llcp_sock->ssap, llcp_sock->service_name...

Regards,
kiyin.

> -Original Message-
> From: Xiaoming Ni [mailto:nixiaom...@huawei.com]
> Sent: Wednesday, March 3, 2021 2:17 PM
> To: linux-kernel@vger.kernel.org; kiyin(尹亮) ;
> sta...@vger.kernel.org; gre...@linuxfoundation.org; sa...@linux.intel.com;
> linvi...@tuxdriver.com; da...@davemloft.net; k...@kernel.org;
> m...@pengutronix.de; ste...@datenfreihafen.org;
> matthieu.bae...@tessares.net; net...@vger.kernel.org
> Cc: nixiaom...@huawei.com; wang...@huawei.com; xiaoqi...@huawei.com
> Subject: [PATCH 4/4] nfc: Avoid endless loops caused by repeated
> llcp_sock_connect()(Internet mail)
> 
> When sock_wait_state() returns -EINPROGRESS, "sk->sk_state" is
> LLCP_CONNECTING. In this case, llcp_sock_connect() is repeatedly invoked,
>  nfc_llcp_sock_link() will add sk to local->connecting_sockets twice.
>  sk->sk_node->next will point to itself, that will make an endless loop  and
> hang-up the system.
> To fix it, check whether sk->sk_state is LLCP_CONNECTING in
>  llcp_sock_connect() to avoid repeated invoking.
> 
> fix CVE-2020-25673
> Fixes: b4011239a08e ("NFC: llcp: Fix non blocking sockets connections")
> Reported-by: "kiyin(尹亮)" 
> Link: https://www.openwall.com/lists/oss-security/2020/11/01/1
> Cc:  #v3.11
> Signed-off-by: Xiaoming Ni 
> ---
>  net/nfc/llcp_sock.c | 4 
>  1 file changed, 4 insertions(+)
> 
> diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c index
> 59172614b249..a3b46f03 100644
> --- a/net/nfc/llcp_sock.c
> +++ b/net/nfc/llcp_sock.c
> @@ -673,6 +673,10 @@ static int llcp_sock_connect(struct socket *sock,
> struct sockaddr *_addr,
>   ret = -EISCONN;
>   goto error;
>   }
> + if (sk->sk_state == LLCP_CONNECTING) {
> + ret = -EINPROGRESS;
> + goto error;
> + }
> 
>   dev = nfc_get_device(addr->dev_idx);
>   if (dev == NULL) {
> --
> 2.27.0
>

[PATCH 4/4] nfc: Avoid endless loops caused by repeated llcp_sock_connect()

2021-03-03 Thread Xiaoming Ni 
When sock_wait_state() returns -EINPROGRESS, "sk->sk_state" is
 LLCP_CONNECTING. In this case, llcp_sock_connect() is repeatedly invoked,
 nfc_llcp_sock_link() will add sk to local->connecting_sockets twice.
 sk->sk_node->next will point to itself, that will make an endless loop
 and hang-up the system.
To fix it, check whether sk->sk_state is LLCP_CONNECTING in
 llcp_sock_connect() to avoid repeated invoking.

fix CVE-2020-25673
Fixes: b4011239a08e ("NFC: llcp: Fix non blocking sockets connections")
Reported-by: "kiyin(尹亮)" 
Link: https://www.openwall.com/lists/oss-security/2020/11/01/1
Cc:  #v3.11
Signed-off-by: Xiaoming Ni 
---
 net/nfc/llcp_sock.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index 59172614b249..a3b46f03 100644
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -673,6 +673,10 @@ static int llcp_sock_connect(struct socket *sock, struct 
sockaddr *_addr,
ret = -EISCONN;
goto error;
}
+   if (sk->sk_state == LLCP_CONNECTING) {
+   ret = -EINPROGRESS;
+   goto error;
+   }
 
dev = nfc_get_device(addr->dev_idx);
if (dev == NULL) {
-- 
2.27.0