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From: Pavel Skripkin <paskripkin@gmail.com>
To: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
	Larry.Finger@lwfinger.net, phil@philpotter.co.uk,
	gregkh@linuxfoundation.org, straube.linux@gmail.com
Cc: linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org,
	Martin Kaiser <martin@kaiser.cx>
Subject: Re: [PATCH RFC 0/3] staging: r8188eu: avoid uninit value bugs
Date: Sun, 22 Aug 2021 13:09:29 +0300	[thread overview]
Message-ID: <ae27d6a0-dc00-459f-7b36-acf7f4c08d72@gmail.com> (raw)
In-Reply-To: <10584649.zhyk0TxWeL@localhost.localdomain>

On 8/22/21 12:53 PM, Fabio M. De Francesco wrote:
> On Friday, August 20, 2021 7:07:28 PM CEST Pavel Skripkin wrote:
>> Hi, Greg, Larry and Phillip!
>> 
>> I noticed, that new staging driver was added like 3 weeks ago and I decided
>> to look at the code, because drivers in staging directory are always buggy.
>> 
>> The first thing I noticed is *no one* was checking read operations result, 
> but
>> it can fail and driver may start writing random stack values into registers. 
> It
>> can cause driver misbehavior or device misbehavior.
> 
> After the messages I wrote yesterday, I had some minutes to look deeper at the
> code that would be changed by these patches.
> 
> I think that it does not look like that the driver could return "random stack
> values into registers" and I think this entire series in unnecessary.
> 
> As far as I understand this driver (though I must admit that I really don't
> know how to write drivers, and I'm not interested in understanding - at the
> moment, at least), all the usb_read*() call usbctrl_vendorreq() and the latter
> *does* proper error checking before returning to the callers the read data.
> 
> Please, look at the code copied from usbctrl_vendorreq() and pasted here (some
> comments are mine):
> 
> /* start of code */
> static int usbctrl_vendorreq(struct intf_hdl *pintfhdl, u16 value, void
> *pdata, u16 len, u8 requesttype)
> {
> 
> /* test if everything is OK for transfers and setup the necessary variables */
> [...]
> 
> status = usb_control_msg(udev, pipe, REALTEK_USB_VENQT_CMD_REQ,
>                                           reqtype, value,
> REALTEK_USB_VENQT_CMD_IDX,
>                                           pIo_buf, len,
> RTW_USB_CONTROL_MSG_TIMEOUT);
> 
>                  if (status == len) {   /*  Success this control transfer. */
>                          rtw_reset_continual_urb_error(dvobjpriv);
>                          if (requesttype == 0x01)
>                                  memcpy(pdata, pIo_buf,  len); /* pdata
> receives the read data */
> 	} else { /*  error cases */
> 
> [...]
> 
> }
> /* end of code */
> 
> So, *I cannot ack this RFC*, unless maintainers say I'm missing something.
> 
> Larry, Philip, since you have much more knowledge than me about r8188eu (and,
> more in general, on device drivers) may you please say what you think about my
> arguments against this series?
> 

Hi, Fabio!

Thank you for looking into this, but I still can see the case when pdata 
won't be initialized:


pdata is initialized only in case of successful transfer, i.e len > 0. 
It means some data was received (maybe not full length, but anyway). In 
case of usb_control_msg() error (for example -ENOMEM) code only does 
this code block:

if (status < 0) {
	if (status == (-ESHUTDOWN) || status == -ENODEV) {
		adapt->bSurpriseRemoved = true;
	} else {
		struct hal_data_8188e	*haldata = GET_HAL_DATA(adapt);
		haldata->srestpriv.Wifi_Error_Status = USB_VEN_REQ_CMD_FAIL;
	}
}


And then just loops further. In case of 10 ENOMEM in a row,. passed 
pdata won't be initialized at all and driver doesn't do anything about 
it. I believe, it's not good approach to play with random values. We 
should somehow handle transfer errors all across the driver.

If I am missing something, please, let me know :)



With regards,
Pavel Skripkin

  reply	other threads:[~2021-08-22 10:09 UTC|newest]

Thread overview: 118+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-20 17:07 Pavel Skripkin
2021-08-20 17:07 ` [PATCH RFC 1/3] staging: r8188eu: add proper rtw_read* error handling Pavel Skripkin
2021-08-20 21:50   ` Pavel Skripkin
2021-08-20 23:41   ` Phillip Potter
2021-08-21  5:55   ` Fabio M. De Francesco
2021-08-21 10:35     ` Pavel Skripkin
2021-08-21 12:11       ` Fabio M. De Francesco
2021-08-20 17:07 ` [PATCH RFC 2/3] staging: r8188eu: add error handling to ReadFuse Pavel Skripkin
2021-08-20 23:51   ` Phillip Potter
2021-08-21  3:59     ` Fabio M. De Francesco
2021-08-20 17:07 ` [PATCH RFC 3/3] staging: r8188eu: add error argument to read_macreg Pavel Skripkin
2021-08-20 23:18   ` Phillip Potter
2021-08-21 10:38     ` Pavel Skripkin
2021-08-20 23:12 ` [PATCH RFC 0/3] staging: r8188eu: avoid uninit value bugs Phillip Potter
2021-08-21 10:42   ` Pavel Skripkin
2021-08-22  9:53 ` Fabio M. De Francesco
2021-08-22 10:09   ` Pavel Skripkin [this message]
2021-08-22 10:59     ` Fabio M. De Francesco
2021-08-22 11:34       ` Fabio M. De Francesco
2021-08-22 12:10       ` Pavel Skripkin
2021-08-22 12:39         ` Greg KH
2021-08-22 12:50           ` Pavel Skripkin
2021-08-22 13:06             ` Greg KH
2021-08-22 13:21           ` Fabio M. De Francesco
2021-08-22 13:30             ` Greg KH
2021-08-22 13:31             ` Pavel Skripkin
2021-08-22 14:35               ` [PATCH RFC v2 0/6] " Pavel Skripkin
2021-08-22 14:35                 ` [PATCH RFC v2 1/6] staging: r8188eu: remove {read,write}_macreg Pavel Skripkin
2021-08-22 14:35                 ` [PATCH RFC v2 2/6] staging: r8188eu: add helper macro for printing registers Pavel Skripkin
2021-08-22 14:35                 ` [PATCH RFC v2 3/6] staging: r8188eu: add error handling of rtw_read8 Pavel Skripkin
2021-08-22 14:35                 ` [PATCH RFC v2 4/6] staging: r8188eu: add error handling of rtw_read16 Pavel Skripkin
2021-08-22 14:36                 ` [PATCH RFC v2 5/6] staging: r8188eu: add error handling of rtw_read32 Pavel Skripkin
2021-08-23 23:33                   ` Phillip Potter
2021-08-24  0:10                     ` Fabio M. De Francesco
2021-08-24  6:40                       ` Pavel Skripkin
2021-08-24  8:38                         ` Fabio M. De Francesco
2021-08-24  8:47                           ` Pavel Skripkin
2021-08-24  8:53                             ` Pavel Skripkin
2021-08-24  9:46                               ` Fabio M. De Francesco
2021-08-24 22:10                               ` Phillip Potter
2021-08-24 22:07                             ` Phillip Potter
2021-08-24  6:53                     ` Pavel Skripkin
2021-08-24  7:25                     ` [PATCH v3 0/6] staging: r8188eu: avoid uninit value bugs Pavel Skripkin
2021-08-24  7:27                       ` [PATCH v3 1/6] staging: r8188eu: remove {read,write}_macreg Pavel Skripkin
2021-08-26 10:39                         ` Greg KH
2021-08-26 10:40                         ` Greg KH
2021-08-24  7:27                       ` [PATCH v3 2/6] staging: r8188eu: add helper macro for printing registers Pavel Skripkin
2021-08-26 10:37                         ` Greg KH
2021-08-24  7:27                       ` [PATCH v3 3/6] staging: r8188eu: add error handling of rtw_read8 Pavel Skripkin
2021-08-25 12:05                         ` kernel test robot
2021-08-25 12:17                           ` Pavel Skripkin
2021-08-25 12:51                             ` Dan Carpenter
2021-08-25 13:02                               ` Pavel Skripkin
2021-08-25 13:34                                 ` Dan Carpenter
2021-08-25 13:44                                   ` Pavel Skripkin
2021-08-25 17:11                                     ` Nick Desaulniers
2021-08-26 11:08                                       ` Dan Carpenter
2021-08-25 23:45                         ` Fabio M. De Francesco
2021-08-26  5:13                           ` Pavel Skripkin
2021-08-26  8:21                         ` David Laight
2021-08-26  8:27                           ` Pavel Skripkin
2021-08-26 10:19                             ` David Laight
2021-08-26 11:21                               ` Dan Carpenter
2021-08-27  8:14                                 ` David Laight
2021-08-27  8:22                                   ` Pavel Skripkin
2021-08-27  9:07                         ` Dan Carpenter
2021-08-27  9:16                           ` Pavel Skripkin
2021-08-27  9:23                             ` Dan Carpenter
2021-08-30 11:21                         ` kernel test robot
2021-08-24  7:27                       ` [PATCH v3 4/6] staging: r8188eu: add error handling of rtw_read16 Pavel Skripkin
2021-08-25  4:35                         ` Fabio M. De Francesco
2021-08-25  8:22                           ` Pavel Skripkin
2021-08-25  9:48                             ` Fabio M. De Francesco
2021-08-25  9:55                               ` Pavel Skripkin
2021-08-25 10:06                                 ` Dan Carpenter
2021-08-25 10:13                                   ` Pavel Skripkin
2021-08-25 10:38                                     ` Dan Carpenter
2021-08-25 10:41                                       ` Pavel Skripkin
2021-08-25 11:06                                       ` Fabio M. De Francesco
2021-08-25 11:11                                         ` Fabio M. De Francesco
2021-08-25 11:31                                         ` Dan Carpenter
2021-08-25 12:11                                           ` Fabio M. De Francesco
2021-08-25 10:51                                 ` Fabio M. De Francesco
2021-08-26 10:50                         ` Greg KH
2021-08-26 10:58                           ` Pavel Skripkin
2021-08-24  7:27                       ` [PATCH v3 5/6] staging: r8188eu: add error handling of rtw_read32 Pavel Skripkin
2021-08-25  4:40                         ` Fabio M. De Francesco
2021-08-26  8:51                         ` David Laight
2021-08-26  9:22                           ` Pavel Skripkin
2021-08-26  9:27                             ` Pavel Skripkin
2021-08-26 10:22                               ` David Laight
2021-08-26 10:55                                 ` Pavel Skripkin
2021-08-26 10:59                                   ` David Laight
2021-08-26 20:03                                     ` Pavel Skripkin
2021-08-27  7:12                                       ` gregkh
2021-08-27  7:16                                         ` Pavel Skripkin
2021-08-24  7:27                       ` [PATCH v3 6/6] staging: r8188eu: make ReadEFuse return an int Pavel Skripkin
2021-08-25 10:13                       ` [PATCH v3 0/6] staging: r8188eu: avoid uninit value bugs Fabio M. De Francesco
2021-08-27  7:49                       ` Kari Argillander
2021-08-27  7:52                         ` Pavel Skripkin
2021-08-24  6:58                   ` [PATCH RFC v2 5/6] staging: r8188eu: add error handling of rtw_read32 Dan Carpenter
2021-08-24  7:01                     ` Pavel Skripkin
2021-08-24 15:07                       ` Fabio M. De Francesco
2021-08-22 14:36                 ` [PATCH RFC v2 6/6] staging: r8188eu: make ReadEFuse return an int Pavel Skripkin
2021-08-22 15:30                 ` [PATCH RFC v2 0/6] staging: r8188eu: avoid uninit value bugs Pavel Skripkin
2021-08-22 16:05                   ` Michael Straube
2021-08-22 16:26                     ` Pavel Skripkin
2021-08-22 23:52                       ` Phillip Potter
2021-08-22 17:36                 ` Fabio M. De Francesco
2021-08-22 17:38                   ` Pavel Skripkin
2021-08-22 20:06                     ` Fabio M. De Francesco
2021-08-22 20:19                       ` Pavel Skripkin
2021-08-23  0:12                 ` Phillip Potter
2021-08-23  6:38                   ` Pavel Skripkin
2021-08-23  6:44                   ` Pavel Skripkin
2021-08-22 16:03               ` [PATCH RFC 0/3] " Fabio M. De Francesco
2021-08-22 16:15                 ` Pavel Skripkin
2021-08-22 15:04             ` Phillip Potter

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