linux-kernel - Re: Hi (Assigning NULL to variable after freeing it).

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Message-ID: <CANYSmhE-O6gH+yPQtOA_vhNJr6coaeNADOBQ0_r=dps_0P48wQ@mail.gmail.com>
Date:   Sat, 27 Jan 2018 17:36:42 +0530
From:   George B <gb4838913@...il.com>
To:     linux-kernel@...r.kernel.org
Subject: Re: Hi (Assigning NULL to variable after freeing it).

>> I have just started to contribute to linux kernel. I was thinking of
>> giving a patch where a variable is made null after free if not already
>> done.
>>

> General answer is no... unless that particular code expects a freed pointer
> to be null. In many cases the code is written so that this isn't needed,
> so you would have to check each usage on a case-by-case basis.

The answer "no" is overconfidence. Linux kernel should be doing
defensive programming. Not setting the variable to NULL after freeing
it is non-defensive programming.

I know that linux kernel developers think that they are the "best in
the world" but this is not true. There are many better developers
around the world and they do set the variable to NULL after freeing
it.

Even in linux kernel itself, many developers set the variable to NULL
after freeing it. This should become a standard.

But I know that linux kernel developers are obstinate and hence they
will not agree to this.

I hate "many" linux kernel developers because of their arrogance but I
do not hate those linux kernel developers who are not arrogant or
egoist.

Many people believe that setting a variable to NULL after freeing it
is totally justified and should be done. Here is a wikipedia page to
make this case stronger:
https://en.wikipedia.org/wiki/Dangling_pointer

But I know that linux kernel developers are obstinate, arrogant, and
egoists and hence they are not going to agree to this.

George