Re: kfree a pointer "from the middle" causing protection faults

[Dmitry Torokhov]

On Wed, Sep 2, 2015 at 8:02 AM, Muni Sekhar <munisekharrms@xxxxxxxxx> wrote:
>  [ Please keep me in CC as I'm not subscribed to the list]
>
> Hello,
>
>
> I am getting protection faults in different kernel modules if I try to
> free a pointer "from the middle" for example, look at the following
> code:
>
>
> u8 *buf;
>
>
> buf = kzalloc( 100 , GFP_KERNEL );
>
> â
>
> buf = buf + 50;
>
> â
>
> Kfree(buf);
>
>
>
>
> I would like to know, why the above code is causing protection faults
> in other kernel modules?

Because you can not make a "hole" in returned memory like that, you
can only free entire block allocated by k*alloc and you need to pass
the original pointer in.

Thanks.

-- 
Dmitry
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