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Date:   Fri, 20 Nov 2020 08:56:11 -0800
In-Reply-To: <20201120165609.GE619708@rowland.harvard.edu>
Message-ID: <000000000000c49c8b05b48cb833@google.com>
Subject: Re: Re: memory leak in hub_event
From:   syzbot <syzbot+44e64397bd81d5e84cba@syzkaller.appspotmail.com>
To:     Alan Stern <stern@rowland.harvard.edu>
Cc:     balbi@kernel.org, gregkh@linuxfoundation.org,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
        stern@rowland.harvard.edu, syzkaller-bugs@googlegroups.com
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> On Fri, Nov 20, 2020 at 07:15:20AM -0800, syzbot wrote:
>> Hello,
>> 
>> syzbot found the following issue on:
>> 
>> HEAD commit:    4d02da97 Merge tag 'net-5.10-rc5' of git://git.kernel.org/..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=13a7d2b6500000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=c5353ac514ca5a43
>> dashboard link: https://syzkaller.appspot.com/bug?extid=44e64397bd81d5e84cba
>> compiler:       gcc (GCC) 10.1.0-syz 20200507
>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14925089500000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16810051500000
>> 
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+44e64397bd81d5e84cba@syzkaller.appspotmail.com
>> 
>> BUG: memory leak
>> unreferenced object 0xffff88810d5ff800 (size 2048):
>>   comm "kworker/1:0", pid 17, jiffies 4294949188 (age 14.280s)
>>   hex dump (first 32 bytes):
>>     ff ff ff ff 31 00 00 00 00 00 00 00 00 00 00 00  ....1...........
>>     00 00 00 00 00 00 00 00 00 00 00 00 03 00 00 00  ................
>>   backtrace:
>>     [<00000000f0428224>] kmalloc include/linux/slab.h:552 [inline]
>>     [<00000000f0428224>] kzalloc include/linux/slab.h:664 [inline]
>>     [<00000000f0428224>] usb_alloc_dev+0x32/0x450 drivers/usb/core/usb.c:582
>>     [<000000001802b3dd>] hub_port_connect drivers/usb/core/hub.c:5128 [inline]
>>     [<000000001802b3dd>] hub_port_connect_change drivers/usb/core/hub.c:5362 [inline]
>>     [<000000001802b3dd>] port_event drivers/usb/core/hub.c:5508 [inline]
>>     [<000000001802b3dd>] hub_event+0x118d/0x20d0 drivers/usb/core/hub.c:5590
>>     [<0000000092d3650d>] process_one_work+0x27d/0x590 kernel/workqueue.c:2272
>>     [<00000000d4629ab0>] worker_thread+0x59/0x5d0 kernel/workqueue.c:2418
>>     [<000000003c358b45>] kthread+0x178/0x1b0 kernel/kthread.c:292
>>     [<000000003689dbb0>] ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
>
> This looks like a reference is being taken but not released.  Hard to 
> tell where it's happening, though.  Let's try to narrow it down.
>
> Alan Stern
>
> #syz test: upstream 4d02da97

"upstream" does not look like a valid git repo address.

>
> Index: usb-devel/drivers/media/usb/gspca/gspca.c
> ===================================================================
> --- usb-devel.orig/drivers/media/usb/gspca/gspca.c
> +++ usb-devel/drivers/media/usb/gspca/gspca.c
> @@ -1489,6 +1489,8 @@ int gspca_dev_probe2(struct usb_interfac
>  	}
>  
>  	gspca_dev->v4l2_dev.release = gspca_release;
> +	ret = -EIO;
> +	goto out;
>  	ret = v4l2_device_register(&intf->dev, &gspca_dev->v4l2_dev);
>  	if (ret)
>  		goto out;