Re: [PATCH net V2] tuntap: correctly wake up process during uninit

[David Miller]

From: Jason Wang 
Date: Thu, 19 May 2016 13:36:51 +0800

> We used to check dev->reg_state against NETREG_REGISTERED after each
> time we are woke up. But after commit 9e641bdcfa4e ("net-tun:
> restructure tun_do_read for better sleep/wakeup efficiency"), it uses
> skb_recv_datagram() which does not check dev->reg_state. This will
> result if we delete a tun/tap device after a process is blocked in the
> reading. The device will wait for the reference count which was held
> by that process for ever.
> 
> Fixes this by using RCV_SHUTDOWN which will be checked during
> sk_recv_datagram() before trying to wake up the process during uninit.
> 
> Fixes: 9e641bdcfa4e ("net-tun: restructure tun_do_read for better
> sleep/wakeup efficiency")
> Cc: Eric Dumazet 
> Cc: Xi Wang 
> Cc: Michael S. Tsirkin 
> Signed-off-by: Jason Wang 
> ---
> - The patch is needed for -stable.
> - Changes from v1: remove unnecessary NETREG_REGISTERED check in tun_do_read()

Applied and queued up for -stable.

Re: [PATCH net V2] tuntap: correctly wake up process during uninit

[David Miller]

From: Jason Wang 
Date: Thu, 19 May 2016 13:36:51 +0800

> We used to check dev->reg_state against NETREG_REGISTERED after each
> time we are woke up. But after commit 9e641bdcfa4e ("net-tun:
> restructure tun_do_read for better sleep/wakeup efficiency"), it uses
> skb_recv_datagram() which does not check dev->reg_state. This will
> result if we delete a tun/tap device after a process is blocked in the
> reading. The device will wait for the reference count which was held
> by that process for ever.
> 
> Fixes this by using RCV_SHUTDOWN which will be checked during
> sk_recv_datagram() before trying to wake up the process during uninit.
> 
> Fixes: 9e641bdcfa4e ("net-tun: restructure tun_do_read for better
> sleep/wakeup efficiency")
> Cc: Eric Dumazet 
> Cc: Xi Wang 
> Cc: Michael S. Tsirkin 
> Signed-off-by: Jason Wang 
> ---
> - The patch is needed for -stable.
> - Changes from v1: remove unnecessary NETREG_REGISTERED check in tun_do_read()

Applied and queued up for -stable.

Re: [PATCH net V2] tuntap: correctly wake up process during uninit

[Michael S. Tsirkin]

On Thu, May 19, 2016 at 01:36:51PM +0800, Jason Wang wrote:
> We used to check dev->reg_state against NETREG_REGISTERED after each
> time we are woke up. But after commit 9e641bdcfa4e ("net-tun:
> restructure tun_do_read for better sleep/wakeup efficiency"), it uses
> skb_recv_datagram() which does not check dev->reg_state. This will
> result if we delete a tun/tap device after a process is blocked in the
> reading. The device will wait for the reference count which was held
> by that process for ever.
> 
> Fixes this by using RCV_SHUTDOWN which will be checked during
> sk_recv_datagram() before trying to wake up the process during uninit.
> 
> Fixes: 9e641bdcfa4e ("net-tun: restructure tun_do_read for better
> sleep/wakeup efficiency")
> Cc: Eric Dumazet 
> Cc: Xi Wang 
> Cc: Michael S. Tsirkin 
> Signed-off-by: Jason Wang 

Acked-by: Michael S. Tsirkin 

> ---
> - The patch is needed for -stable.
> - Changes from v1: remove unnecessary NETREG_REGISTERED check in tun_do_read()
> ---
>  drivers/net/tun.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 425e983..e16487c 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -580,11 +580,13 @@ static void tun_detach_all(struct net_device *dev)
>   for (i = 0; i < n; i++) {
>   tfile = rtnl_dereference(tun->tfiles[i]);
>   BUG_ON(!tfile);
> + tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
>   tfile->socket.sk->sk_data_ready(tfile->socket.sk);
>   RCU_INIT_POINTER(tfile->tun, NULL);
>   --tun->numqueues;
>   }
>   list_for_each_entry(tfile, >disabled, next) {
> + tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
>   tfile->socket.sk->sk_data_ready(tfile->socket.sk);
>   RCU_INIT_POINTER(tfile->tun, NULL);
>   }
> @@ -641,6 +643,7 @@ static int tun_attach(struct tun_struct *tun, struct file 
> *file, bool skip_filte
>   goto out;
>   }
>   tfile->queue_index = tun->numqueues;
> + tfile->socket.sk->sk_shutdown &= ~RCV_SHUTDOWN;
>   rcu_assign_pointer(tfile->tun, tun);
>   rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
>   tun->numqueues++;
> @@ -1491,9 +1494,6 @@ static ssize_t tun_do_read(struct tun_struct *tun, 
> struct tun_file *tfile,
>   if (!iov_iter_count(to))
>   return 0;
>  
> - if (tun->dev->reg_state != NETREG_REGISTERED)
> - return -EIO;
> -
>   /* Read frames from queue */
>   skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
> , , );
> -- 
> 2.7.4

Re: [PATCH net V2] tuntap: correctly wake up process during uninit

[Michael S. Tsirkin]

On Thu, May 19, 2016 at 01:36:51PM +0800, Jason Wang wrote:
> We used to check dev->reg_state against NETREG_REGISTERED after each
> time we are woke up. But after commit 9e641bdcfa4e ("net-tun:
> restructure tun_do_read for better sleep/wakeup efficiency"), it uses
> skb_recv_datagram() which does not check dev->reg_state. This will
> result if we delete a tun/tap device after a process is blocked in the
> reading. The device will wait for the reference count which was held
> by that process for ever.
> 
> Fixes this by using RCV_SHUTDOWN which will be checked during
> sk_recv_datagram() before trying to wake up the process during uninit.
> 
> Fixes: 9e641bdcfa4e ("net-tun: restructure tun_do_read for better
> sleep/wakeup efficiency")
> Cc: Eric Dumazet 
> Cc: Xi Wang 
> Cc: Michael S. Tsirkin 
> Signed-off-by: Jason Wang 

Acked-by: Michael S. Tsirkin 

> ---
> - The patch is needed for -stable.
> - Changes from v1: remove unnecessary NETREG_REGISTERED check in tun_do_read()
> ---
>  drivers/net/tun.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 425e983..e16487c 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -580,11 +580,13 @@ static void tun_detach_all(struct net_device *dev)
>   for (i = 0; i < n; i++) {
>   tfile = rtnl_dereference(tun->tfiles[i]);
>   BUG_ON(!tfile);
> + tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
>   tfile->socket.sk->sk_data_ready(tfile->socket.sk);
>   RCU_INIT_POINTER(tfile->tun, NULL);
>   --tun->numqueues;
>   }
>   list_for_each_entry(tfile, >disabled, next) {
> + tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
>   tfile->socket.sk->sk_data_ready(tfile->socket.sk);
>   RCU_INIT_POINTER(tfile->tun, NULL);
>   }
> @@ -641,6 +643,7 @@ static int tun_attach(struct tun_struct *tun, struct file 
> *file, bool skip_filte
>   goto out;
>   }
>   tfile->queue_index = tun->numqueues;
> + tfile->socket.sk->sk_shutdown &= ~RCV_SHUTDOWN;
>   rcu_assign_pointer(tfile->tun, tun);
>   rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
>   tun->numqueues++;
> @@ -1491,9 +1494,6 @@ static ssize_t tun_do_read(struct tun_struct *tun, 
> struct tun_file *tfile,
>   if (!iov_iter_count(to))
>   return 0;
>  
> - if (tun->dev->reg_state != NETREG_REGISTERED)
> - return -EIO;
> -
>   /* Read frames from queue */
>   skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
> , , );
> -- 
> 2.7.4

Re: [PATCH net V2] tuntap: correctly wake up process during uninit

[Eric Dumazet]

On Thu, 2016-05-19 at 13:36 +0800, Jason Wang wrote:
> We used to check dev->reg_state against NETREG_REGISTERED after each
> time we are woke up. But after commit 9e641bdcfa4e ("net-tun:
> restructure tun_do_read for better sleep/wakeup efficiency"), it uses
> skb_recv_datagram() which does not check dev->reg_state. This will
> result if we delete a tun/tap device after a process is blocked in the
> reading. The device will wait for the reference count which was held
> by that process for ever.
> 
> Fixes this by using RCV_SHUTDOWN which will be checked during
> sk_recv_datagram() before trying to wake up the process during uninit.
> 
> Fixes: 9e641bdcfa4e ("net-tun: restructure tun_do_read for better
> sleep/wakeup efficiency")
> Cc: Eric Dumazet 
> Cc: Xi Wang 
> Cc: Michael S. Tsirkin 
> Signed-off-by: Jason Wang 
> ---

Acked-by: Eric Dumazet 

Thanks !

Re: [PATCH net V2] tuntap: correctly wake up process during uninit

[Eric Dumazet]

On Thu, 2016-05-19 at 13:36 +0800, Jason Wang wrote:
> We used to check dev->reg_state against NETREG_REGISTERED after each
> time we are woke up. But after commit 9e641bdcfa4e ("net-tun:
> restructure tun_do_read for better sleep/wakeup efficiency"), it uses
> skb_recv_datagram() which does not check dev->reg_state. This will
> result if we delete a tun/tap device after a process is blocked in the
> reading. The device will wait for the reference count which was held
> by that process for ever.
> 
> Fixes this by using RCV_SHUTDOWN which will be checked during
> sk_recv_datagram() before trying to wake up the process during uninit.
> 
> Fixes: 9e641bdcfa4e ("net-tun: restructure tun_do_read for better
> sleep/wakeup efficiency")
> Cc: Eric Dumazet 
> Cc: Xi Wang 
> Cc: Michael S. Tsirkin 
> Signed-off-by: Jason Wang 
> ---

Acked-by: Eric Dumazet 

Thanks !

[PATCH net V2] tuntap: correctly wake up process during uninit

[Jason Wang]

We used to check dev->reg_state against NETREG_REGISTERED after each
time we are woke up. But after commit 9e641bdcfa4e ("net-tun:
restructure tun_do_read for better sleep/wakeup efficiency"), it uses
skb_recv_datagram() which does not check dev->reg_state. This will
result if we delete a tun/tap device after a process is blocked in the
reading. The device will wait for the reference count which was held
by that process for ever.

Fixes this by using RCV_SHUTDOWN which will be checked during
sk_recv_datagram() before trying to wake up the process during uninit.

Fixes: 9e641bdcfa4e ("net-tun: restructure tun_do_read for better
sleep/wakeup efficiency")
Cc: Eric Dumazet 
Cc: Xi Wang 
Cc: Michael S. Tsirkin 
Signed-off-by: Jason Wang 
---
- The patch is needed for -stable.
- Changes from v1: remove unnecessary NETREG_REGISTERED check in tun_do_read()
---
 drivers/net/tun.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 425e983..e16487c 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -580,11 +580,13 @@ static void tun_detach_all(struct net_device *dev)
for (i = 0; i < n; i++) {
tfile = rtnl_dereference(tun->tfiles[i]);
BUG_ON(!tfile);
+   tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
tfile->socket.sk->sk_data_ready(tfile->socket.sk);
RCU_INIT_POINTER(tfile->tun, NULL);
--tun->numqueues;
}
list_for_each_entry(tfile, >disabled, next) {
+   tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
tfile->socket.sk->sk_data_ready(tfile->socket.sk);
RCU_INIT_POINTER(tfile->tun, NULL);
}
@@ -641,6 +643,7 @@ static int tun_attach(struct tun_struct *tun, struct file 
*file, bool skip_filte
goto out;
}
tfile->queue_index = tun->numqueues;
+   tfile->socket.sk->sk_shutdown &= ~RCV_SHUTDOWN;
rcu_assign_pointer(tfile->tun, tun);
rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
tun->numqueues++;
@@ -1491,9 +1494,6 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct 
tun_file *tfile,
if (!iov_iter_count(to))
return 0;
 
-   if (tun->dev->reg_state != NETREG_REGISTERED)
-   return -EIO;
-
/* Read frames from queue */
skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
  , , );
-- 
2.7.4

[PATCH net V2] tuntap: correctly wake up process during uninit

[Jason Wang]

We used to check dev->reg_state against NETREG_REGISTERED after each
time we are woke up. But after commit 9e641bdcfa4e ("net-tun:
restructure tun_do_read for better sleep/wakeup efficiency"), it uses
skb_recv_datagram() which does not check dev->reg_state. This will
result if we delete a tun/tap device after a process is blocked in the
reading. The device will wait for the reference count which was held
by that process for ever.

Fixes this by using RCV_SHUTDOWN which will be checked during
sk_recv_datagram() before trying to wake up the process during uninit.

Fixes: 9e641bdcfa4e ("net-tun: restructure tun_do_read for better
sleep/wakeup efficiency")
Cc: Eric Dumazet 
Cc: Xi Wang 
Cc: Michael S. Tsirkin 
Signed-off-by: Jason Wang 
---
- The patch is needed for -stable.
- Changes from v1: remove unnecessary NETREG_REGISTERED check in tun_do_read()
---
 drivers/net/tun.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 425e983..e16487c 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -580,11 +580,13 @@ static void tun_detach_all(struct net_device *dev)
for (i = 0; i < n; i++) {
tfile = rtnl_dereference(tun->tfiles[i]);
BUG_ON(!tfile);
+   tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
tfile->socket.sk->sk_data_ready(tfile->socket.sk);
RCU_INIT_POINTER(tfile->tun, NULL);
--tun->numqueues;
}
list_for_each_entry(tfile, >disabled, next) {
+   tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
tfile->socket.sk->sk_data_ready(tfile->socket.sk);
RCU_INIT_POINTER(tfile->tun, NULL);
}
@@ -641,6 +643,7 @@ static int tun_attach(struct tun_struct *tun, struct file 
*file, bool skip_filte
goto out;
}
tfile->queue_index = tun->numqueues;
+   tfile->socket.sk->sk_shutdown &= ~RCV_SHUTDOWN;
rcu_assign_pointer(tfile->tun, tun);
rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
tun->numqueues++;
@@ -1491,9 +1494,6 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct 
tun_file *tfile,
if (!iov_iter_count(to))
return 0;
 
-   if (tun->dev->reg_state != NETREG_REGISTERED)
-   return -EIO;
-
/* Read frames from queue */
skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
  , , );
-- 
2.7.4