From: Jason Wang <jasowang@xxxxxxxxxx>
This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit addf8fc4acb1cf79492ac64966f07178793cb3d7 ]
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 <edumazet@xxxxxxxxxx>
Cc: Xi Wang <xii@xxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
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 9dd3746..a4685a2 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -499,11 +499,13 @@ 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, &tun->disabled, next) {
+ tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
tfile->socket.sk->sk_data_ready(tfile->socket.sk);
RCU_INIT_POINTER(tfile->tun, NULL);
}
@@ -558,6 +560,7 @@ 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++;
@@ -1356,9 +1359,6 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
if (!len)
return ret;
- if (tun->dev->reg_state != NETREG_REGISTERED)
- return -EIO;
-
/* Read frames from queue */
skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
&peeked, &off, &err);
--
2.5.0
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html