[PATCH 00/14] Make the user mode driver code a better citizen

[Tetsuo Handa]

On 2020/07/01 1:48, Alexei Starovoitov wrote:
> On Tue, Jun 30, 2020 at 03:28:49PM +0900, Tetsuo Handa wrote:
>> On 2020/06/30 5:19, Eric W. Biederman wrote:
>>> Tetsuo Handa <penguin-kernel at i-love.sakura.ne.jp> writes:
>>>
>>>> On 2020/06/29 4:44, Alexei Starovoitov wrote:
>>>>> But all the defensive programming kinda goes against general kernel style.
>>>>> I wouldn't do it. Especially pr_info() ?!
>>>>> Though I don't feel strongly about it.
>>>>
>>>> Honestly speaking, caller should check for errors and print appropriate
>>>> messages. info->wd.mnt->mnt_root != info->wd.dentry indicates that something
>>>> went wrong (maybe memory corruption). But other conditions are not fatal.
>>>> That is, I consider even pr_info() here should be unnecessary.
>>>
>>> They were all should never happen cases.  Which is why my patches do:
>>> if (WARN_ON_ONCE(...))
>>
>> No. Fuzz testing (which uses panic_on_warn=1) will trivially hit them.
> 
> I don't believe that's true.
> Please show fuzzing stack trace to prove your point.
> 

Please find links containing "WARNING" from https://syzkaller.appspot.com/upstream . ;-)