WARNING in hso_free_net_device

[syzbot]

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+44d53c...@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..


---
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[Hui Peng]

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 ?

[Stephen Hemminger]

On Wed, 4 Sep 2019 16:27:50 -0400
Hui Peng <benq...@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

[Hui Peng]

Can you guys have  a look at the attached patch?

[Andrey Konovalov]

On Thu, Sep 5, 2019 at 4:20 AM Hui Peng <benq...@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

[syzbot]

Hello,

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

Reported-and-tested-by:
syzbot+44d53c...@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.

[Hui Peng]

On 9/5/2019 7:24 AM, Andrey Konovalov wrote:
> On Thu, Sep 5, 2019 at 4:20 AM Hui Peng <benq...@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.

[Oliver Neukum]

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 <benq...@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