LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Hui Peng <benquike@gmail.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: syzbot+44d53c7255bb1aea22d2@syzkaller.appspotmail.com,
	alexios.zavras@intel.com, andreyknvl@google.com,
	davem@davemloft.net, gregkh@linuxfoundation.org,
	linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
	mathias.payer@nebelwelt.net, netdev@vger.kernel.org,
	rfontana@redhat.com, syzkaller-bugs@googlegroups.com,
	tglx@linutronix.de
Subject: Re: WARNING in hso_free_net_device
Date: Wed, 4 Sep 2019 22:20:23 -0400
Message-ID: <285edb24-01f9-3f9d-4946-b2f41ccd0774@gmail.com> (raw)
In-Reply-To: <20190904154140.45dfb398@hermes.lan>

[-- Attachment #1: Type: text/plain, Size: 882 bytes --]

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@gmail.com> 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

[-- Warning: decoded text below may be mangled --]
[-- Attachment #2: 0001-Fix-a-wrong-unregistering-bug-in-hso_free_net_device.patch --]
[-- Type: text/x-patch; name="0001-Fix-a-wrong-unregistering-bug-in-hso_free_net_device.patch", Size: 2399 bytes --]

From f3fdee8fc03aa2bc982f22da1d29bbf6bca72935 Mon Sep 17 00:00:00 2001
From: Hui Peng <benquike@gmail.com>
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@syzkaller.appspotmail.com
Signed-off-by: Hui Peng <benquike@gmail.com>
---
 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 #3: pEpkey.asc --]
[-- Type: application/pgp-keys, Size: 2489 bytes --]

  reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-03 12:08 syzbot
2019-09-04 20:27 ` Hui Peng
2019-09-04 22:41   ` Stephen Hemminger
2019-09-05  2:20     ` Hui Peng [this message]
2019-09-05 11:24       ` Andrey Konovalov
2019-09-05 11:47         ` syzbot
2019-09-06  2:05         ` Hui Peng
2019-09-09  9:47           ` Oliver Neukum

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=285edb24-01f9-3f9d-4946-b2f41ccd0774@gmail.com \
    --to=benquike@gmail.com \
    --cc=alexios.zavras@intel.com \
    --cc=andreyknvl@google.com \
    --cc=davem@davemloft.net \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-usb@vger.kernel.org \
    --cc=mathias.payer@nebelwelt.net \
    --cc=netdev@vger.kernel.org \
    --cc=rfontana@redhat.com \
    --cc=stephen@networkplumber.org \
    --cc=syzbot+44d53c7255bb1aea22d2@syzkaller.appspotmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --cc=tglx@linutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git