[Patch net] tipc: call start and done ops directly in __tipc_nl_compat_dumpit()

[Patch net] tipc: call start and done ops directly in __tipc_nl_compat_dumpit()

[Cong Wang]

__tipc_nl_compat_dumpit() uses a netlink_callback on stack,
so the only way to align it with other ->dumpit() call path
is calling tipc_dump_start() and tipc_dump_done() directly
inside it. Otherwise ->dumpit() would always get NULL from
cb->args[0].

But, tipc_dump_start() uses sock_net(cb->skb->sk) to retrieve
net pointer, the cb->skb here doesn't set ->sk, the net pointer
is saved in msg->net instead, so introduce a helper function
__tipc_dump_start() to pass in msg->net.

Fixes: 9a07efa9aea2 ("tipc: switch to rhashtable iterator")
Reported-by: syzbot+e93a2c41f91b8e2c7d9b@syzkaller.appspotmail.com
Cc: Jon Maloy <jon.maloy@ericsson.com>
Cc: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
 net/tipc/netlink_compat.c | 2 ++
 net/tipc/socket.c         | 8 ++++++--
 net/tipc/socket.h         | 1 +
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
index a2f76743c73a..82f665728382 100644
--- a/net/tipc/netlink_compat.c
+++ b/net/tipc/netlink_compat.c
@@ -185,6 +185,7 @@ static int __tipc_nl_compat_dumpit(struct tipc_nl_compat_cmd_dump *cmd,
 		return -ENOMEM;
 
 	buf->sk = msg->dst_sk;
+	__tipc_dump_start(&cb, msg->net);
 
 	do {
 		int rem;
@@ -216,6 +217,7 @@ static int __tipc_nl_compat_dumpit(struct tipc_nl_compat_cmd_dump *cmd,
 	err = 0;
 
 err_out:
+	tipc_dump_done(&cb);
 	kfree_skb(buf);
 
 	if (err == -EMSGSIZE) {
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index ab7a2a7178f7..a19b2b1c77ed 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -3264,9 +3264,14 @@ int tipc_nl_sk_walk(struct sk_buff *skb, struct netlink_callback *cb,
 EXPORT_SYMBOL(tipc_nl_sk_walk);
 
 int tipc_dump_start(struct netlink_callback *cb)
+{
+	return __tipc_dump_start(cb, sock_net(cb->skb->sk));
+}
+EXPORT_SYMBOL(tipc_dump_start);
+
+int __tipc_dump_start(struct netlink_callback *cb, struct net *net)
 {
 	struct rhashtable_iter *iter = (void *)cb->args[0];
-	struct net *net = sock_net(cb->skb->sk);
 	struct tipc_net *tn = tipc_net(net);
 
 	if (!iter) {
@@ -3280,7 +3285,6 @@ int tipc_dump_start(struct netlink_callback *cb)
 	rhashtable_walk_enter(&tn->sk_rht, iter);
 	return 0;
 }
-EXPORT_SYMBOL(tipc_dump_start);
 
 int tipc_dump_done(struct netlink_callback *cb)
 {
diff --git a/net/tipc/socket.h b/net/tipc/socket.h
index d43032e26532..5e575f205afe 100644
--- a/net/tipc/socket.h
+++ b/net/tipc/socket.h
@@ -69,5 +69,6 @@ int tipc_nl_sk_walk(struct sk_buff *skb, struct netlink_callback *cb,
 				       struct netlink_callback *cb,
 				       struct tipc_sock *tsk));
 int tipc_dump_start(struct netlink_callback *cb);
+int __tipc_dump_start(struct netlink_callback *cb, struct net *net);
 int tipc_dump_done(struct netlink_callback *cb);
 #endif
-- 
2.14.4

[Patch net] tipc: orphan sock in tipc_release()

[Cong Wang]

Before we unlock the sock in tipc_release(), we have to
detach sk->sk_socket from sk, otherwise a parallel
tipc_sk_fill_sock_diag() could stil read it after we
free this socket.

Fixes: c30b70deb5f4 ("tipc: implement socket diagnostics for AF_TIPC")
Reported-and-tested-by: syzbot+48804b87c16588ad491d@syzkaller.appspotmail.com
Cc: Jon Maloy <jon.maloy@ericsson.com>
Cc: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
 net/tipc/socket.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index a19b2b1c77ed..b5a6635e4dfa 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -576,6 +576,7 @@ static int tipc_release(struct socket *sock)
 	sk_stop_timer(sk, &sk->sk_timer);
 	tipc_sk_remove(tsk);
 
+	sock_orphan(sk);
 	/* Reject any messages that accumulated in backlog queue */
 	release_sock(sk);
 	tipc_dest_list_purge(&tsk->cong_links);
-- 
2.14.4

Re: [Patch net] tipc: call start and done ops directly in __tipc_nl_compat_dumpit()

[Ying Xue]

On 09/04/2018 10:12 AM, Cong Wang wrote:
> __tipc_nl_compat_dumpit() uses a netlink_callback on stack,
> so the only way to align it with other ->dumpit() call path
> is calling tipc_dump_start() and tipc_dump_done() directly
> inside it. Otherwise ->dumpit() would always get NULL from
> cb->args[0].

Thank you for your fix Cong!

Your solution is fine with me.

When we align __tipc_nl_compat_dumpit() with ->dumpit() functions
defined in tipc_genl_v2_ops[], cb->args[0] is used to save a
rhashtable_iter object allocated in tipc_dump_start(), and the object
will be retrieved with cb->args[0] in tipc_dump_done() and will be freed.

But unfortunately cb->args[0] has been used to other purposes in
tipc_nl_bearer_dump(), tipc_nl_node_dump_link(),
tipc_nl_name_table_dump(), tipc_nl_node_dump() and tipc_nl_net_dump().
It means cb->args[0] saved in __tipc_dump_start() will be overwritten in
these ->dumpit() functions. As a consequence, not only the
rhashtable_iter object allocated in tipc_dump_start() cannot be properly
released in tipc_dump_done(), but also more kernel panics might be
triggered in tipc_dump_done().

> 
> But, tipc_dump_start() uses sock_net(cb->skb->sk) to retrieve
> net pointer, the cb->skb here doesn't set ->sk, the net pointer
> is saved in msg->net instead, so introduce a helper function
> __tipc_dump_start() to pass in msg->net.
> 
> Fixes: 9a07efa9aea2 ("tipc: switch to rhashtable iterator")
> Reported-by: syzbot+e93a2c41f91b8e2c7d9b@syzkaller.appspotmail.com
> Cc: Jon Maloy <jon.maloy@ericsson.com>
> Cc: Ying Xue <ying.xue@windriver.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> ---
>  net/tipc/netlink_compat.c | 2 ++
>  net/tipc/socket.c         | 8 ++++++--
>  net/tipc/socket.h         | 1 +
>  3 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
> index a2f76743c73a..82f665728382 100644
> --- a/net/tipc/netlink_compat.c
> +++ b/net/tipc/netlink_compat.c
> @@ -185,6 +185,7 @@ static int __tipc_nl_compat_dumpit(struct tipc_nl_compat_cmd_dump *cmd,
>  		return -ENOMEM;
>  
>  	buf->sk = msg->dst_sk;
> +	__tipc_dump_start(&cb, msg->net);
>  
>  	do {
>  		int rem;
> @@ -216,6 +217,7 @@ static int __tipc_nl_compat_dumpit(struct tipc_nl_compat_cmd_dump *cmd,
>  	err = 0;
>  
>  err_out:
> +	tipc_dump_done(&cb);
>  	kfree_skb(buf);
>  
>  	if (err == -EMSGSIZE) {
> diff --git a/net/tipc/socket.c b/net/tipc/socket.c
> index ab7a2a7178f7..a19b2b1c77ed 100644
> --- a/net/tipc/socket.c
> +++ b/net/tipc/socket.c
> @@ -3264,9 +3264,14 @@ int tipc_nl_sk_walk(struct sk_buff *skb, struct netlink_callback *cb,
>  EXPORT_SYMBOL(tipc_nl_sk_walk);
>  
>  int tipc_dump_start(struct netlink_callback *cb)
> +{
> +	return __tipc_dump_start(cb, sock_net(cb->skb->sk));
> +}
> +EXPORT_SYMBOL(tipc_dump_start);
> +
> +int __tipc_dump_start(struct netlink_callback *cb, struct net *net)
>  {
>  	struct rhashtable_iter *iter = (void *)cb->args[0];
> -	struct net *net = sock_net(cb->skb->sk);
>  	struct tipc_net *tn = tipc_net(net);
>  
>  	if (!iter) {
> @@ -3280,7 +3285,6 @@ int tipc_dump_start(struct netlink_callback *cb)
>  	rhashtable_walk_enter(&tn->sk_rht, iter);
>  	return 0;
>  }
> -EXPORT_SYMBOL(tipc_dump_start);
>  
>  int tipc_dump_done(struct netlink_callback *cb)
>  {
> diff --git a/net/tipc/socket.h b/net/tipc/socket.h
> index d43032e26532..5e575f205afe 100644
> --- a/net/tipc/socket.h
> +++ b/net/tipc/socket.h
> @@ -69,5 +69,6 @@ int tipc_nl_sk_walk(struct sk_buff *skb, struct netlink_callback *cb,
>  				       struct netlink_callback *cb,
>  				       struct tipc_sock *tsk));
>  int tipc_dump_start(struct netlink_callback *cb);
> +int __tipc_dump_start(struct netlink_callback *cb, struct net *net);
>  int tipc_dump_done(struct netlink_callback *cb);
>  #endif
> 

Re: [Patch net] tipc: orphan sock in tipc_release()

[Ying Xue]

On 09/04/2018 10:12 AM, Cong Wang wrote:
> Before we unlock the sock in tipc_release(), we have to
> detach sk->sk_socket from sk, otherwise a parallel
> tipc_sk_fill_sock_diag() could stil read it after we
> free this socket.
> 
> Fixes: c30b70deb5f4 ("tipc: implement socket diagnostics for AF_TIPC")
> Reported-and-tested-by: syzbot+48804b87c16588ad491d@syzkaller.appspotmail.com
> Cc: Jon Maloy <jon.maloy@ericsson.com>
> Cc: Ying Xue <ying.xue@windriver.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>

Acked-by: Ying Xue <ying.xue@windriver.com>

> ---
>  net/tipc/socket.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/tipc/socket.c b/net/tipc/socket.c
> index a19b2b1c77ed..b5a6635e4dfa 100644
> --- a/net/tipc/socket.c
> +++ b/net/tipc/socket.c
> @@ -576,6 +576,7 @@ static int tipc_release(struct socket *sock)
>  	sk_stop_timer(sk, &sk->sk_timer);
>  	tipc_sk_remove(tsk);
>  
> +	sock_orphan(sk);
>  	/* Reject any messages that accumulated in backlog queue */
>  	release_sock(sk);
>  	tipc_dest_list_purge(&tsk->cong_links);
> 

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Re: [Patch net] tipc: call start and done ops directly in __tipc_nl_compat_dumpit()

[Cong Wang]

On Tue, Sep 4, 2018 at 4:45 AM Ying Xue <ying.xue@windriver.com> wrote:
>
>
> On 09/04/2018 10:12 AM, Cong Wang wrote:
> > __tipc_nl_compat_dumpit() uses a netlink_callback on stack,
> > so the only way to align it with other ->dumpit() call path
> > is calling tipc_dump_start() and tipc_dump_done() directly
> > inside it. Otherwise ->dumpit() would always get NULL from
> > cb->args[0].
>
> Thank you for your fix Cong!
>
> Your solution is fine with me.
>
> When we align __tipc_nl_compat_dumpit() with ->dumpit() functions
> defined in tipc_genl_v2_ops[], cb->args[0] is used to save a
> rhashtable_iter object allocated in tipc_dump_start(), and the object
> will be retrieved with cb->args[0] in tipc_dump_done() and will be freed.
>
> But unfortunately cb->args[0] has been used to other purposes in
> tipc_nl_bearer_dump(), tipc_nl_node_dump_link(),
> tipc_nl_name_table_dump(), tipc_nl_node_dump() and tipc_nl_net_dump().
> It means cb->args[0] saved in __tipc_dump_start() will be overwritten in
> these ->dumpit() functions. As a consequence, not only the
> rhashtable_iter object allocated in tipc_dump_start() cannot be properly
> released in tipc_dump_done(), but also more kernel panics might be
> triggered in tipc_dump_done().

Ah, good catch!

The max utilization of cb->args is tipc_nl_name_table_dump():

net/tipc/name_table.c:  cb->args[0] = last_type;
net/tipc/name_table.c:  cb->args[1] = last_lower;
net/tipc/name_table.c:  cb->args[2] = last_key;
net/tipc/name_table.c:  cb->args[3] = done;

Looks like I should just use cb->args[4] for rhashtable iterator,
as we still have some room in cb->args[].

Re: [Patch net] tipc: orphan sock in tipc_release()

[David Miller]

From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Mon,  3 Sep 2018 19:12:41 -0700

> Before we unlock the sock in tipc_release(), we have to
> detach sk->sk_socket from sk, otherwise a parallel
> tipc_sk_fill_sock_diag() could stil read it after we
> free this socket.
> 
> Fixes: c30b70deb5f4 ("tipc: implement socket diagnostics for AF_TIPC")
> Reported-and-tested-by: syzbot+48804b87c16588ad491d@syzkaller.appspotmail.com
> Cc: Jon Maloy <jon.maloy@ericsson.com>
> Cc: Ying Xue <ying.xue@windriver.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>

Applied and queued up for -stable, thanks.