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* WARNING in hso_free_net_device
@ 2019-09-03 12:08 syzbot
  2019-09-04 20:27 ` Hui Peng
  0 siblings, 1 reply; 8+ messages in thread
From: syzbot @ 2019-09-03 12:08 UTC (permalink / raw)
  To: alexios.zavras, andreyknvl, benquike, davem, gregkh,
	linux-kernel, linux-usb, mathias.payer, netdev, rfontana,
	syzkaller-bugs, tglx

Hello,

syzbot found the following crash on:

HEAD commit:    eea39f24 usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=15f17e61600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d0c62209eedfd54e
dashboard link: https://syzkaller.appspot.com/bug?extid=44d53c7255bb1aea22d2
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10ffdd12600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15a738fe600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+44d53c7255bb1aea22d2@syzkaller.appspotmail.com

usb 1-1: config 0 has no interface number 0
usb 1-1: New USB device found, idVendor=0af0, idProduct=d257,  
bcdDevice=4e.87
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
hso 1-1:0.15: Can't find BULK IN endpoint
------------[ cut here ]------------
WARNING: CPU: 1 PID: 83 at net/core/dev.c:8167  
rollback_registered_many.cold+0x41/0x1bc net/core/dev.c:8167
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 83 Comm: kworker/1:2 Not tainted 5.3.0-rc5+ #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0xca/0x13e lib/dump_stack.c:113
  panic+0x2a3/0x6da kernel/panic.c:219
  __warn.cold+0x20/0x4a kernel/panic.c:576
  report_bug+0x262/0x2a0 lib/bug.c:186
  fixup_bug arch/x86/kernel/traps.c:179 [inline]
  fixup_bug arch/x86/kernel/traps.c:174 [inline]
  do_error_trap+0x12b/0x1e0 arch/x86/kernel/traps.c:272
  do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:291
  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:rollback_registered_many.cold+0x41/0x1bc net/core/dev.c:8167
Code: ff e8 c7 26 90 fc 48 c7 c7 40 ec 63 86 e8 24 c8 7a fc 0f 0b e9 93 be  
ff ff e8 af 26 90 fc 48 c7 c7 40 ec 63 86 e8 0c c8 7a fc <0f> 0b 4c 89 e7  
e8 f9 12 34 fd 31 ff 41 89 c4 89 c6 e8 bd 27 90 fc
RSP: 0018:ffff8881d934f088 EFLAGS: 00010282
RAX: 0000000000000024 RBX: ffff8881d2ad4400 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81288cfd RDI: ffffed103b269e03
RBP: ffff8881d934f1b8 R08: 0000000000000024 R09: fffffbfff11ad794
R10: fffffbfff11ad793 R11: ffffffff88d6bc9f R12: ffff8881d2ad4470
R13: ffff8881d934f148 R14: dffffc0000000000 R15: 0000000000000000
  rollback_registered+0xf2/0x1c0 net/core/dev.c:8243
  unregister_netdevice_queue net/core/dev.c:9290 [inline]
  unregister_netdevice_queue+0x1d7/0x2b0 net/core/dev.c:9283
  unregister_netdevice include/linux/netdevice.h:2631 [inline]
  unregister_netdev+0x18/0x20 net/core/dev.c:9331
  hso_free_net_device+0xff/0x300 drivers/net/usb/hso.c:2366
  hso_create_net_device+0x76d/0x9c0 drivers/net/usb/hso.c:2554
  hso_probe+0x28d/0x1a46 drivers/net/usb/hso.c:2931
  usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
  really_probe+0x281/0x6d0 drivers/base/dd.c:548
  driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
  bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454
  __device_attach+0x217/0x360 drivers/base/dd.c:894
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
  device_add+0xae6/0x16f0 drivers/base/core.c:2165
  usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023
  generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
  usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
  really_probe+0x281/0x6d0 drivers/base/dd.c:548
  driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
  bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454
  __device_attach+0x217/0x360 drivers/base/dd.c:894
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
  device_add+0xae6/0x16f0 drivers/base/core.c:2165
  usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2536
  hub_port_connect drivers/usb/core/hub.c:5098 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
  port_event drivers/usb/core/hub.c:5359 [inline]
  hub_event+0x1b5c/0x3640 drivers/usb/core/hub.c:5441
  process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
  worker_thread+0x96/0xe20 kernel/workqueue.c:2415
  kthread+0x318/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: WARNING in hso_free_net_device
  2019-09-03 12:08 WARNING in hso_free_net_device syzbot
@ 2019-09-04 20:27 ` Hui Peng
  2019-09-04 22:41   ` Stephen Hemminger
  0 siblings, 1 reply; 8+ messages in thread
From: Hui Peng @ 2019-09-04 20:27 UTC (permalink / raw)
  To: syzbot+44d53c7255bb1aea22d2, alexios.zavras, andreyknvl, davem,
	gregkh, linux-kernel, linux-usb, mathias.payer, netdev, rfontana,
	syzkaller-bugs, tglx

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 ?

On 9/3/19 8:08 AM, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    eea39f24 usb-fuzzer: main usb gadget fuzzer driver
> git tree:       https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=15f17e61600000
> kernel config: 
> https://syzkaller.appspot.com/x/.config?x=d0c62209eedfd54e
> dashboard link:
> https://syzkaller.appspot.com/bug?extid=44d53c7255bb1aea22d2
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:     
> https://syzkaller.appspot.com/x/repro.syz?x=10ffdd12600000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15a738fe600000
>
> IMPORTANT: if you fix the bug, please add the following tag to the
> commit:
> Reported-by: syzbot+44d53c7255bb1aea22d2@syzkaller.appspotmail.com
>
> usb 1-1: config 0 has no interface number 0
> usb 1-1: New USB device found, idVendor=0af0, idProduct=d257,
> bcdDevice=4e.87
> usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
> usb 1-1: config 0 descriptor??
> hso 1-1:0.15: Can't find BULK IN endpoint
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 83 at net/core/dev.c:8167
> rollback_registered_many.cold+0x41/0x1bc net/core/dev.c:8167
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 1 PID: 83 Comm: kworker/1:2 Not tainted 5.3.0-rc5+ #28
> Hardware name: Google Google Compute Engine/Google Compute Engine,
> BIOS Google 01/01/2011
> Workqueue: usb_hub_wq hub_event
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0xca/0x13e lib/dump_stack.c:113
>  panic+0x2a3/0x6da kernel/panic.c:219
>  __warn.cold+0x20/0x4a kernel/panic.c:576
>  report_bug+0x262/0x2a0 lib/bug.c:186
>  fixup_bug arch/x86/kernel/traps.c:179 [inline]
>  fixup_bug arch/x86/kernel/traps.c:174 [inline]
>  do_error_trap+0x12b/0x1e0 arch/x86/kernel/traps.c:272
>  do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:291
>  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
> RIP: 0010:rollback_registered_many.cold+0x41/0x1bc net/core/dev.c:8167
> Code: ff e8 c7 26 90 fc 48 c7 c7 40 ec 63 86 e8 24 c8 7a fc 0f 0b e9
> 93 be ff ff e8 af 26 90 fc 48 c7 c7 40 ec 63 86 e8 0c c8 7a fc <0f> 0b
> 4c 89 e7 e8 f9 12 34 fd 31 ff 41 89 c4 89 c6 e8 bd 27 90 fc
> RSP: 0018:ffff8881d934f088 EFLAGS: 00010282
> RAX: 0000000000000024 RBX: ffff8881d2ad4400 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffffffff81288cfd RDI: ffffed103b269e03
> RBP: ffff8881d934f1b8 R08: 0000000000000024 R09: fffffbfff11ad794
> R10: fffffbfff11ad793 R11: ffffffff88d6bc9f R12: ffff8881d2ad4470
> R13: ffff8881d934f148 R14: dffffc0000000000 R15: 0000000000000000
>  rollback_registered+0xf2/0x1c0 net/core/dev.c:8243
>  unregister_netdevice_queue net/core/dev.c:9290 [inline]
>  unregister_netdevice_queue+0x1d7/0x2b0 net/core/dev.c:9283
>  unregister_netdevice include/linux/netdevice.h:2631 [inline]
>  unregister_netdev+0x18/0x20 net/core/dev.c:9331
>  hso_free_net_device+0xff/0x300 drivers/net/usb/hso.c:2366
>  hso_create_net_device+0x76d/0x9c0 drivers/net/usb/hso.c:2554
>  hso_probe+0x28d/0x1a46 drivers/net/usb/hso.c:2931
>  usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
>  really_probe+0x281/0x6d0 drivers/base/dd.c:548
>  driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721
>  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
>  bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454
>  __device_attach+0x217/0x360 drivers/base/dd.c:894
>  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
>  device_add+0xae6/0x16f0 drivers/base/core.c:2165
>  usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023
>  generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
>  usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
>  really_probe+0x281/0x6d0 drivers/base/dd.c:548
>  driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721
>  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
>  bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454
>  __device_attach+0x217/0x360 drivers/base/dd.c:894
>  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
>  device_add+0xae6/0x16f0 drivers/base/core.c:2165
>  usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2536
>  hub_port_connect drivers/usb/core/hub.c:5098 [inline]
>  hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
>  port_event drivers/usb/core/hub.c:5359 [inline]
>  hub_event+0x1b5c/0x3640 drivers/usb/core/hub.c:5441
>  process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
>  worker_thread+0x96/0xe20 kernel/workqueue.c:2415
>  kthread+0x318/0x420 kernel/kthread.c:255
>  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: WARNING in hso_free_net_device
  2019-09-04 20:27 ` Hui Peng
@ 2019-09-04 22:41   ` Stephen Hemminger
  2019-09-05  2:20     ` Hui Peng
  0 siblings, 1 reply; 8+ messages in thread
From: Stephen Hemminger @ 2019-09-04 22:41 UTC (permalink / raw)
  To: Hui Peng
  Cc: syzbot+44d53c7255bb1aea22d2, alexios.zavras, andreyknvl, davem,
	gregkh, linux-kernel, linux-usb, mathias.payer, netdev, rfontana,
	syzkaller-bugs, tglx

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

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: WARNING in hso_free_net_device
  2019-09-04 22:41   ` Stephen Hemminger
@ 2019-09-05  2:20     ` Hui Peng
  2019-09-05 11:24       ` Andrey Konovalov
  0 siblings, 1 reply; 8+ messages in thread
From: Hui Peng @ 2019-09-05  2:20 UTC (permalink / raw)
  To: Stephen Hemminger
  Cc: syzbot+44d53c7255bb1aea22d2, alexios.zavras, andreyknvl, davem,
	gregkh, linux-kernel, linux-usb, mathias.payer, netdev, rfontana,
	syzkaller-bugs, tglx

[-- 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 --]

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: WARNING in hso_free_net_device
  2019-09-05  2:20     ` Hui Peng
@ 2019-09-05 11:24       ` Andrey Konovalov
  2019-09-05 11:47         ` syzbot
  2019-09-06  2:05         ` Hui Peng
  0 siblings, 2 replies; 8+ messages in thread
From: Andrey Konovalov @ 2019-09-05 11:24 UTC (permalink / raw)
  To: Hui Peng
  Cc: Stephen Hemminger, syzbot+44d53c7255bb1aea22d2, alexios.zavras,
	David S. Miller, Greg Kroah-Hartman, LKML, USB list,
	Mathias Payer, netdev, rfontana, syzkaller-bugs, Thomas Gleixner,
	Oliver Neukum

[-- Attachment #1: Type: text/plain, Size: 1328 bytes --]

On Thu, Sep 5, 2019 at 4:20 AM Hui Peng <benquike@gmail.com> wrote:
>
> Can you guys have  a look at the attached patch?

Let's try it:

#syz test: https://github.com/google/kasan.git eea39f24

FYI: there are two more reports coming from this driver, which might
(or might not) have the same root cause. One of them has a suggested
fix by Oliver.

https://syzkaller.appspot.com/bug?extid=67b2bd0e34f952d0321e
https://syzkaller.appspot.com/bug?extid=93f2f45b19519b289613

>
> 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

[-- Attachment #2: 0001-Fix-a-wrong-unregistering-bug-in-hso_free_net_device.patch --]
[-- Type: text/x-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


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: WARNING in hso_free_net_device
  2019-09-05 11:24       ` Andrey Konovalov
@ 2019-09-05 11:47         ` syzbot
  2019-09-06  2:05         ` Hui Peng
  1 sibling, 0 replies; 8+ messages in thread
From: syzbot @ 2019-09-05 11:47 UTC (permalink / raw)
  To: alexios.zavras, andreyknvl, benquike, davem, gregkh,
	linux-kernel, linux-usb, mathias.payer, netdev, oneukum,
	rfontana, stephen, syzkaller-bugs, tglx

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger  
crash:

Reported-and-tested-by:  
syzbot+44d53c7255bb1aea22d2@syzkaller.appspotmail.com

Tested on:

commit:         eea39f24 usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan.git
kernel config:  https://syzkaller.appspot.com/x/.config?x=d0c62209eedfd54e
dashboard link: https://syzkaller.appspot.com/bug?extid=44d53c7255bb1aea22d2
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1188fcc6600000

Note: testing is done by a robot and is best-effort only.

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: WARNING in hso_free_net_device
  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
  1 sibling, 1 reply; 8+ messages in thread
From: Hui Peng @ 2019-09-06  2:05 UTC (permalink / raw)
  To: Andrey Konovalov
  Cc: Stephen Hemminger, syzbot+44d53c7255bb1aea22d2, alexios.zavras,
	David S. Miller, Greg Kroah-Hartman, LKML, USB list,
	Mathias Payer, netdev, rfontana, syzkaller-bugs, Thomas Gleixner,
	Oliver Neukum



On 9/5/2019 7:24 AM, Andrey Konovalov wrote:
> On Thu, Sep 5, 2019 at 4:20 AM Hui Peng <benquike@gmail.com> wrote:
>>
>> Can you guys have  a look at the attached patch?
> 
> Let's try it:
> 
> #syz test: https://github.com/google/kasan.git eea39f24
> 
> FYI: there are two more reports coming from this driver, which might
> (or might not) have the same root cause. One of them has a suggested
> fix by Oliver.
> 
> https://syzkaller.appspot.com/bug?extid=67b2bd0e34f952d0321e
> https://syzkaller.appspot.com/bug?extid=93f2f45b19519b289613
> 

I think they are different, though similar.
This one is resulted from unregistering a network device.
These 2 are resulted from unregistering a tty device.

>>
>> 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

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: WARNING in hso_free_net_device
  2019-09-06  2:05         ` Hui Peng
@ 2019-09-09  9:47           ` Oliver Neukum
  0 siblings, 0 replies; 8+ messages in thread
From: Oliver Neukum @ 2019-09-09  9:47 UTC (permalink / raw)
  To: Hui Peng, Andrey Konovalov
  Cc: David S. Miller, syzkaller-bugs, alexios.zavras, Thomas Gleixner,
	Greg Kroah-Hartman, Mathias Payer, Stephen Hemminger, rfontana,
	syzbot+44d53c7255bb1aea22d2, LKML, USB list, netdev

Am Donnerstag, den 05.09.2019, 22:05 -0400 schrieb Hui Peng:
> 
> On 9/5/2019 7:24 AM, Andrey Konovalov wrote:
> > On Thu, Sep 5, 2019 at 4:20 AM Hui Peng <benquike@gmail.com> wrote:
> > > 
> > > Can you guys have  a look at the attached patch?
> > 
> > Let's try it:
> > 
> > #syz test: https://github.com/google/kasan.git eea39f24
> > 
> > FYI: there are two more reports coming from this driver, which might
> > (or might not) have the same root cause. One of them has a suggested
> > fix by Oliver.
> > 
> > https://syzkaller.appspot.com/bug?extid=67b2bd0e34f952d0321e
> > https://syzkaller.appspot.com/bug?extid=93f2f45b19519b289613
> > 
> 
> I think they are different, though similar.
> This one is resulted from unregistering a network device.
> These 2 are resulted from unregistering a tty device.

Hi,

looks like it. That may indeed be the issue.
Please try to have syzbot test your patch and we will
know more.

	Regards
		Oliver


^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, back to index

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-03 12:08 WARNING in hso_free_net_device syzbot
2019-09-04 20:27 ` Hui Peng
2019-09-04 22:41   ` Stephen Hemminger
2019-09-05  2:20     ` Hui Peng
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

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