linux-kernel - Re: [PATCH] tty: vt: keyboard: Free dynamic-memory only if kmalloc'ed.

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Date:   Sat, 6 Nov 2021 16:13:48 +0530
From:   Ajay Garg <ajaygargnsit@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tty: vt: keyboard: Free dynamic-memory only if kmalloc'ed.

Thanks, will ensure that I run scripts/checkpatch.pl before posting
any patch from now on.

The v2 patch is posted at :
https://lore.kernel.org/linux-serial/20211106104053.98761-1-ajaygargnsit@gmail.com/T/#u

On Sat, Nov 6, 2021 at 3:11 PM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Sat, Nov 06, 2021 at 03:02:02PM +0530, Ajay Garg wrote:
> > In "vt_do_kdgkb_ioctl", kbs is kmalloced, if cmd is one of
> > KDGKBSENT or KDGSKBSENT.
> >
> > If cmd is none of the above, no kbs is kmalloced, and thus,
> > kbs must only be kfreed if it is really kmalloced.
> >
> > Signed-off-by: Ajay Garg <ajaygargnsit@...il.com>
> > ---
> >  drivers/tty/vt/keyboard.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
> > index dfef7de8a057..95839987c79c 100644
> > --- a/drivers/tty/vt/keyboard.c
> > +++ b/drivers/tty/vt/keyboard.c
> > @@ -2049,7 +2049,7 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
> >  {
> >       unsigned char kb_func;
> >       unsigned long flags;
> > -     char *kbs;
> > +     char *kbs = NULL;
> >       int ret;
> >
> >       if (get_user(kb_func, &user_kdgkb->kb_func))
> > @@ -2092,7 +2092,8 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
> >               break;
> >       }
> >
> > -     kfree(kbs);
> > +        if(kbs)
> > +            kfree(kbs);
> >
> >       return ret;
> >  }
> > --
> > 2.30.2
> >
>
>
> Hi,
>
> This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
> a patch that has triggered this response.  He used to manually respond
> to these common problems, but in order to save his sanity (he kept
> writing the same thing over and over, yet to different people), I was
> created.  Hopefully you will not take offence and will fix the problem
> in your patch and resubmit it so that it can be accepted into the Linux
> kernel tree.
>
> You are receiving this message because of the following common error(s)
> as indicated below:
>
> - Your patch contains warnings and/or errors noticed by the
>   scripts/checkpatch.pl tool.
>
> If you wish to discuss this problem further, or you have questions about
> how to resolve this issue, please feel free to respond to this email and
> Greg will reply once he has dug out from the pending patches received
> from other developers.
>
> thanks,
>
> greg k-h's patch email bot