linux-kernel - Re: Setting variable NULL after freeing it.

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Message-ID: <20221112113410.GA5553@1wt.eu>
Date:   Sat, 12 Nov 2022 12:34:10 +0100
From:   Willy Tarreau <w@....eu>
To:     A <amit234234234234@...il.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: Setting variable NULL after freeing it.

On Sat, Nov 12, 2022 at 04:18:37PM +0530, A wrote:
> >
> > It depends. What's important is not to let a pointer exist to a freed
> > location, so if you're doing:
> >
> >     kfree(card->pool);
> >
> > then it's usually important to follow this by:
> >
> >     card->pool = NULL;
> >
> 
> I checked in kernel but at many places this is not being done. I can
> change all that code. But, will the patch be accepted?
> 
> So, if someone is doing -
> 
> kfree(x)
> ._some_code_
> ._some_code_
> ._some_code_
> 
> Then I can change it to -
> 
> kfree(x)
> x = NULL;
> ._some_code_
> ._some_code_
> ._some_code_
> 
> But, will the patch be accepted for this change?

I don't think so, for the reasons I explained previously,
unless you spot real bugs there during your reviews, of
course. Better focus on your own driver for now in my
opinion.

Willy