linux-kernel - Re: [PATCH RFC 0/3] staging: r8188eu: avoid uninit value bugs

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Date:   Sat, 21 Aug 2021 13:42:30 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     Phillip Potter <phil@...lpotter.co.uk>
Cc:     linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Larry.Finger@...inger.net, gregkh@...uxfoundation.org,
        straube.linux@...il.com, fmdefrancesco@...il.com
Subject: Re: [PATCH RFC 0/3] staging: r8188eu: avoid uninit value bugs

On 8/21/21 2:12 AM, Phillip Potter wrote:
> On Fri, 2021-08-20 at 20:07 +0300, 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.
>> 
>> To avoid this type of bugs, i've expanded read() API with error
>> parametr,
>> which will be initialized to error if read fails. It helps callers to
>> break/return earlier and don't write random values to registers or to
>> rely
>> on random values.
>> 
>> Why is this pacth series RFC?
>>   1. I don't have this device and I cannot test these changes.
>>   2. I don't know how to handle errors in each particular case. For
>> now, function
>>      just returns or returns an error. That's all. I hope, driver
>> maintainers will
>>      help with these bits.
>>   3. I guess, I handled not all uninit value bugs here. I hope, I
>> fixed
>>      at least half of them
>> 
>> This series was build-tested and made on top of staging-testing
>> branch
>> 
>> 
>> With regards,
>> Pavel Skripkin
>> 
>> Pavel Skripkin (3):
>>   staging: r8188eu: add proper rtw_read* error handling
>>   staging: r8188eu: add error handling to ReadFuse
>>   staging: r8188eu: add error argument to read_macreg
>> 
>>  drivers/staging/r8188eu/core/rtw_debug.c      |  79 +++-
>>  drivers/staging/r8188eu/core/rtw_efuse.c      | 119 +++--
>>  drivers/staging/r8188eu/core/rtw_io.c         |  18 +-
>>  drivers/staging/r8188eu/core/rtw_mp.c         |  38 +-
>>  drivers/staging/r8188eu/core/rtw_mp_ioctl.c   |  20 +-
>>  drivers/staging/r8188eu/core/rtw_pwrctrl.c    |   6 +-
>>  drivers/staging/r8188eu/core/rtw_sreset.c     |   7 +-
>>  drivers/staging/r8188eu/hal/HalPwrSeqCmd.c    |   9 +-
>>  drivers/staging/r8188eu/hal/hal_com.c         |  22 +-
>>  drivers/staging/r8188eu/hal/hal_intf.c        |   6 +-
>>  drivers/staging/r8188eu/hal/odm_interface.c   |  12 +-
>>  drivers/staging/r8188eu/hal/rtl8188e_cmd.c    |  37 +-
>>  drivers/staging/r8188eu/hal/rtl8188e_dm.c     |   6 +-
>>  .../staging/r8188eu/hal/rtl8188e_hal_init.c   | 260 ++++++++---
>>  drivers/staging/r8188eu/hal/rtl8188e_phycfg.c |  26 +-
>>  drivers/staging/r8188eu/hal/rtl8188e_sreset.c |  20 +-
>>  drivers/staging/r8188eu/hal/rtl8188eu_led.c   |  17 +-
>>  drivers/staging/r8188eu/hal/usb_halinit.c     | 412 ++++++++++++++--
>> --
>>  drivers/staging/r8188eu/hal/usb_ops_linux.c   |  55 ++-
>>  drivers/staging/r8188eu/include/hal_intf.h    |   6 +-
>>  .../staging/r8188eu/include/rtl8188e_hal.h    |   2 +-
>>  drivers/staging/r8188eu/include/rtw_efuse.h   |   4 +-
>>  drivers/staging/r8188eu/include/rtw_io.h      |  18 +-
>>  drivers/staging/r8188eu/include/rtw_mp.h      |   2 +-
>>  drivers/staging/r8188eu/os_dep/ioctl_linux.c  | 168 +++++--
>>  drivers/staging/r8188eu/os_dep/usb_intf.c     |   4 +-
>>  26 files changed, 1072 insertions(+), 301 deletions(-)
>> 
> 
> Dear Pavel,
> 
> Firstly, thank you for this contribution, it is much appreciated.
> Whilst I'm still learning myself when it comes to this driver and to
> kernel code in general, I can certainly say the code looks pretty good
> in general so far. I will try and offer individual comments on each
> patch.
> 

Thank you for your feedback. So, I will prepare a v2 version in few days 
and, I think, I will leave RFC prefix.

Also, I want to receive some feedback from Larry about error handling in 
each particular case, I guess, he can help us with it.

So, I will split each rtw_read* changes into separate patche and make 
them return an error instead of read value.


Again, big thanks to you and Fabio for feedback, I appreciate it :)




With regards,
Pavel Skripkin