[v2] nbd: fix potential NULL pointer fault in nbd_genl_disconnect
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@huawei.com>
---
v1 -> v2:
add an omitted mutex_unlock.
---
drivers/block/nbd.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index b4607dd96185..668bc9cb92ed 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -2008,6 +2008,10 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
index);
return -EINVAL;
}
+ if (!nbd->task_recv) {
+ mutex_unlock(&nbd_index_mutex);
+ return -EINVAL;
+ }
if (!refcount_inc_not_zero(&nbd->refs)) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: device at index %d is going down\n",
--
2.17.2
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