在 2020/2/11 1:05, Mike Christie 写道:
On 02/10/2020 01:32 AM, Sun Ke wrote:
Open /dev/nbdX first, the config_refs will be 1 and
the pointers in nbd_device are still null. Disconnect
/dev/nbdX, then reference a null recv_workq. The
protection by config_refs in nbd_genl_disconnect is useless.
To fix it, just add a check for a non null task_recv in
nbd_genl_disconnect.
Signed-off-by: Sun Ke <sunke32@xxxxxxxxxx>
---
v1 -> v2:
Add an omitted mutex_unlock.
v2 -> v3:
Add nbd->config_lock, suggested by Josef.
---
drivers/block/nbd.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index b4607dd96185..870b3fd0c101 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -2008,12 +2008,20 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
index);
return -EINVAL;
}
+ mutex_lock(&nbd->config_lock);
if (!refcount_inc_not_zero(&nbd->refs)) {
+ mutex_unlock(&nbd->config_lock);
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: device at index %d is going down\n",
index);
return -EINVAL;
}
+ if (!nbd->recv_workq) {
+ mutex_unlock(&nbd->config_lock);
+ mutex_unlock(&nbd_index_mutex);
+ return -EINVAL;
+ }
+ mutex_unlock(&nbd->config_lock);
mutex_unlock(&nbd_index_mutex);
if (!refcount_inc_not_zero(&nbd->config_refs)) {
nbd_put(nbd);
With my other patch then we will not need this right? It handles your
case by just being integrated with the existing checks in:
nbd_disconnect_and_put->nbd_clear_sock->sock_shutdown
...
static void sock_shutdown(struct nbd_device *nbd)
{
....
if (config->num_connections == 0)
return;
num_connections is zero for your case since we never did a
nbd_genl_disconnect so we would return here.
.
Hi Mike
Your point is not right totally.
Yes, config->num_connections is 0 and will return in sock_shutdown. Then
it will back to nbd_disconnect_and_put and do flush_workqueue
(nbd->recv_workq).
nbd_disconnect_and_put
->nbd_clear_sock
->sock_shutdown
->flush_workqueue
Thanks,
Sun Ke
