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Sender: Larry Finger <larry.finger@gmail.com>
Message-ID: <579f78b3-eec5-534d-407f-40216b31c755@lwfinger.net>
Date:   Mon, 17 Apr 2023 10:57:28 -0500
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Subject: Re: [PATCH] wifi: rtw88: Fix memory leak in rtw88_usb
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To:     Ping-Ke Shih <pkshih@realtek.com>, Kalle Valo <kvalo@kernel.org>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>
References: <20230415011422.11162-1-Larry.Finger@lwfinger.net>
 <085f8fe9ec9749689e9f3fc51bfe1cce@realtek.com>
From:   Larry Finger <Larry.Finger@lwfinger.net>
In-Reply-To: <085f8fe9ec9749689e9f3fc51bfe1cce@realtek.com>
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On 4/17/23 01:08, Ping-Ke Shih wrote:
> 
> 
>> -----Original Message-----
>> From: Larry Finger <larry.finger@gmail.com> On Behalf Of Larry Finger
>> Sent: Saturday, April 15, 2023 9:14 AM
>> To: Kalle Valo <kvalo@kernel.org>
>> Cc: Johannes Berg <johannes@sipsolutions.net>; linux-wireless@vger.kernel.org; Larry Finger
>> <Larry.Finger@lwfinger.net>; Sascha Hauer <s.hauer@pengutronix.de>; Ping-Ke Shih <pkshih@realtek.com>
>> Subject: [PATCH] wifi: rtw88: Fix memory leak in rtw88_usb
>>
>> Kmemleak shows the following leak arising from routine in the usb
>> probe routine:
>>
>> unreferenced object 0xffff895cb29bba00 (size 512):
>>    comm "(udev-worker)", pid 534, jiffies 4294903932 (age 102751.088s)
>>    hex dump (first 32 bytes):
>>      77 30 30 30 00 00 00 00 02 2f 2d 2b 30 00 00 00  w000...../-+0...
>>      02 00 2a 28 00 00 00 00 ff 55 ff ff ff 00 00 00  ..*(.....U......
>>    backtrace:
>>      [<ffffffff9265fa36>] kmalloc_trace+0x26/0x90
>>      [<ffffffffc17eec41>] rtw_usb_probe+0x2f1/0x680 [rtw_usb]
>>      [<ffffffffc03e19fd>] usb_probe_interface+0xdd/0x2e0 [usbcore]
>>      [<ffffffff92b4f2fe>] really_probe+0x18e/0x3d0
>>      [<ffffffff92b4f5b8>] __driver_probe_device+0x78/0x160
>>      [<ffffffff92b4f6bf>] driver_probe_device+0x1f/0x90
>>      [<ffffffff92b4f8df>] __driver_attach+0xbf/0x1b0
>>      [<ffffffff92b4d350>] bus_for_each_dev+0x70/0xc0
>>      [<ffffffff92b4e51e>] bus_add_driver+0x10e/0x210
>>      [<ffffffff92b50935>] driver_register+0x55/0xf0
>>      [<ffffffffc03e0708>] usb_register_driver+0x88/0x140 [usbcore]
>>      [<ffffffff92401153>] do_one_initcall+0x43/0x210
>>      [<ffffffff9254f42a>] do_init_module+0x4a/0x200
>>      [<ffffffff92551d1c>] __do_sys_finit_module+0xac/0x120
>>      [<ffffffff92ee6626>] do_syscall_64+0x56/0x80
>>      [<ffffffff9300006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
>>
>> The leak was verified to be real by unloading the driver, which resulted
>> in a dangling pointer to the allocation.
>>
>> The allocated memory is freed in rtw_usb_disconnect().
>>
>> Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
>> Cc: Sascha Hauer <s.hauer@pengutronix.de>
>> Cc: Ping-Ke Shih <pkshih@realtek.com>
>> ---
>>   drivers/net/wireless/realtek/rtw88/usb.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
>> index 68e1b782d199..d28493a8f16c 100644
>> --- a/drivers/net/wireless/realtek/rtw88/usb.c
>> +++ b/drivers/net/wireless/realtek/rtw88/usb.c
>> @@ -882,6 +882,7 @@ void rtw_usb_disconnect(struct usb_interface *intf)
>>          rtw_unregister_hw(rtwdev, hw);
>>          rtw_usb_deinit_tx(rtwdev);
>>          rtw_usb_deinit_rx(rtwdev);
>> +       kfree(rtwusb->usb_data);
> 
> I suggest to do this in rtw_usb_intf_deinit() instead, because rtwusb->usb_data is
> allocated by rtw_usb_intf_init(). Not only make the code symmetric also can handle
> error cases properly of rtw_usb_probe().

Ping-Ke,

Thanks for the suggestion. I chose my location because the allocation was just 
before the call to rtw_usb_init_tx(), thus the free went after 
rtw_usb_deinit_tx(), but I see your point. I will submit v2.

Larry