Can you guys have a look at the attached patch? On 9/4/19 6:41 PM, Stephen Hemminger wrote: > On Wed, 4 Sep 2019 16:27:50 -0400 > Hui Peng <benquike@xxxxxxxxx> wrote: > >> Hi, all: >> >> I looked at the bug a little. >> >> The issue is that in the error handling code, hso_free_net_device >> unregisters >> >> the net_device (hso_net->net) by calling unregister_netdev. In the >> error handling code path, >> >> hso_net->net has not been registered yet. >> >> I think there are two ways to solve the issue: >> >> 1. fix it in drivers/net/usb/hso.c to avoiding unregistering the >> net_device when it is still not registered >> >> 2. fix it in unregister_netdev. We can add a field in net_device to >> record whether it is registered, and make unregister_netdev return if >> the net_device is not registered yet. >> >> What do you guys think ? > #1
From f3fdee8fc03aa2bc982f22da1d29bbf6bca72935 Mon Sep 17 00:00:00 2001
From: Hui Peng <benquike@xxxxxxxxx>
Date: Wed, 4 Sep 2019 21:38:35 -0400
Subject: [PATCH] Fix a wrong unregistering bug in hso_free_net_device
As shown below, hso_create_net_device may call hso_free_net_device
before the net_device is registered. hso_free_net_device will
unregister the network device no matter it is registered or not,
unregister_netdev is not able to handle unregistered net_device,
resulting in the bug reported by the syzbot.
```
static struct hso_device *hso_create_net_device(struct usb_interface *interface,
int port_spec)
{
......
net = alloc_netdev(sizeof(struct hso_net), "hso%d", NET_NAME_UNKNOWN,
hso_net_init);
......
if (!hso_net->out_endp) {
dev_err(&interface->dev, "Can't find BULK OUT endpoint\n");
goto exit;
}
......
result = register_netdev(net);
......
exit:
hso_free_net_device(hso_dev);
return NULL;
}
static void hso_free_net_device(struct hso_device *hso_dev)
{
......
if (hso_net->net)
unregister_netdev(hso_net->net);
......
}
```
This patch adds a net_registered field in struct hso_net to record whether
the containing net_device is registered or not, and avoid unregistering it
if it is not registered yet.
Reported-by: syzbot+44d53c7255bb1aea22d2@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Hui Peng <benquike@xxxxxxxxx>
---
drivers/net/usb/hso.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index ce78714..5b3df33 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -128,6 +128,7 @@ struct hso_shared_int {
struct hso_net {
struct hso_device *parent;
struct net_device *net;
+ bool net_registered;
struct rfkill *rfkill;
char name[24];
@@ -2362,7 +2363,7 @@ static void hso_free_net_device(struct hso_device *hso_dev)
remove_net_device(hso_net->parent);
- if (hso_net->net)
+ if (hso_net->net && hso_net->net_registered)
unregister_netdev(hso_net->net);
/* start freeing */
@@ -2544,6 +2545,7 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface,
dev_err(&interface->dev, "Failed to register device\n");
goto exit;
}
+ hso_net->net_registered = true;
hso_log_port(hso_dev);
--
2.7.4
Attachment:
pEpkey.asc
Description: application/pgp-keys
