Re: usb/gadget: warning in dummy_free_request

[Andrey Konovalov]

On Tue, Dec 27, 2016 at 12:40 PM, Felipe Balbi <balbi@xxxxxxxxxx> wrote:
>
> Hi,
>
> Andrey Konovalov <andreyknvl@xxxxxxxxxx> writes:
>> Hi!
>>
>> I've got the following error report while running the syzkaller fuzzer.
>>
>> On commit 3c49de52d5647cda8b42c4255cf8a29d1e22eff5 (Dec 2).
>>
>> WARNING: CPU: 0 PID: 5257 at drivers/usb/gadget/udc/dummy_hcd.c:672
>> dummy_free_request+0x153/0x170
>> Kernel panic - not syncing: panic_on_warn set ...
>>
>> usb 2-1: string descriptor 0 read error: -71
>> usb 2-1: New USB device found, idVendor=0000, idProduct=0000
>> usb 2-1: New USB device strings: Mfr=0, Product=170, SerialNumber=0
>> CPU: 0 PID: 5257 Comm: syz-executor0 Not tainted 4.9.0-rc7+ #16
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>>  ffff88006af0ec48 ffffffff81f96aba ffffffff00000200 1ffff1000d5e1d1c
>>  ffffed000d5e1d14 0000000000000a06 0000000041b58ab3 ffffffff8598b4c8
>>  ffffffff81f96828 0000000041b58ab3 ffffffff85942a10 ffffffff81432790
>> Call Trace:
>>  [<     inline     >] __dump_stack lib/dump_stack.c:15
>>  [<ffffffff81f96aba>] dump_stack+0x292/0x398 lib/dump_stack.c:51
>>  [<ffffffff8168c7be>] panic+0x1cb/0x3a9 kernel/panic.c:179
>>  [<ffffffff812b80b4>] __warn+0x1c4/0x1e0 kernel/panic.c:542
>>  [<ffffffff812b831c>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585
>>  [<ffffffff830fcac3>] dummy_free_request+0x153/0x170
>> drivers/usb/gadget/udc/dummy_hcd.c:672
>>  [<ffffffff830ed160>] usb_ep_free_request+0xc0/0x420
>> drivers/usb/gadget/udc/core.c:195
>>  [<ffffffff83224fe1>] gadgetfs_unbind+0x131/0x190
>> drivers/usb/gadget/legacy/inode.c:1612
>>  [<ffffffff830ebcbf>] usb_gadget_remove_driver+0x10f/0x2b0
>> drivers/usb/gadget/udc/core.c:1228
>>  [<ffffffff830ec016>] usb_gadget_unregister_driver+0x1b6/0x2c0
>> drivers/usb/gadget/udc/core.c:1357
>>  [<ffffffff83224650>] dev_release+0x80/0x160
>> drivers/usb/gadget/legacy/inode.c:1187
>>  [<ffffffff81805852>] __fput+0x332/0x7f0 fs/file_table.c:208
>>  [<ffffffff81805d95>] ____fput+0x15/0x20 fs/file_table.c:244
>>  [<ffffffff81338b9b>] task_work_run+0x19b/0x270 kernel/task_work.c:116
>>  [<     inline     >] exit_task_work include/linux/task_work.h:21
>>  [<ffffffff812c7eca>] do_exit+0x16aa/0x2530 kernel/exit.c:828
>>  [<ffffffff812cd749>] do_group_exit+0x149/0x420 kernel/exit.c:932
>>  [<ffffffff812faa9d>] get_signal+0x76d/0x17b0 kernel/signal.c:2307
>>  [<ffffffff811cfee2>] do_signal+0xd2/0x2120 arch/x86/kernel/signal.c:807
>>  [<ffffffff81003d00>] exit_to_usermode_loop+0x170/0x200
>> arch/x86/entry/common.c:156
>>  [<     inline     >] prepare_exit_to_usermode arch/x86/entry/common.c:190
>>  [<ffffffff81007293>] syscall_return_slowpath+0x3d3/0x420
>> arch/x86/entry/common.c:259
>>  [<ffffffff84f47f62>] entry_SYSCALL_64_fastpath+0xc0/0xc2
>> Dumping ftrace buffer:
>>    (ftrace buffer empty)
>> Kernel Offset: disabled
>
> There have been several emails like this one. Can you check if
> my branch testing/fixes is working for you?

Hi Felipe,

This was fixed by Alan with the "USB: dummy-hcd: fix bug in
stop_activity (handle ep0)" patch.

Thanks!

>
> --
> balbi
>
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