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Subject: Re: WARNING in hso_free_net_device
To:     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
References: <0000000000002a95df0591a4f114@google.com>
From:   Hui Peng <benquike@gmail.com>
Message-ID: <d6e4d2da-66c6-a8fe-2fea-a3435fa7cb54@gmail.com>
Date:   Wed, 4 Sep 2019 16:27:50 -0400
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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..
>
>
> ---
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>
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