linux-kernel - Re: [PATCH] staging: r8188eu: add a null check of kzalloc in go_add_group_info

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Date:   Mon, 27 Feb 2023 15:11:21 +0800
From:   Kang Chen <void0red@...il.com>
To:     Dan Carpenter <error27@...il.com>
Cc:     paskripkin@...il.com, Larry.Finger@...inger.net,
        phil@...lpotter.co.uk, gregkh@...uxfoundation.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: r8188eu: add a null check of kzalloc in go_add_group_info_attr

Hi, Dan,

Thanks for your review.
I noticed there is no error handling in the origin design (this call chain).
go_add_group_info_attr returns a len-like value indicating the length
of pbuf.
I don't think throwing an error to the caller is a good idea, the caller
doesn't seem to care about it.
So inserting a netdev_dbg or pr_debug here might be enough.
Do you have a better idea?

Best regards,
Kang Chen


On Mon, Feb 27, 2023 at 12:47 PM Dan Carpenter <error27@...il.com> wrote:
>
> On Sun, Feb 26, 2023 at 09:25:00PM +0800, Kang Chen wrote:
> > kzalloc may fails, pdata_attr might be null and will cause
> > illegal address access later.
> >
> > Signed-off-by: Kang Chen <void0red@...il.com>
> > ---
> >  drivers/staging/r8188eu/core/rtw_p2p.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/staging/r8188eu/core/rtw_p2p.c b/drivers/staging/r8188eu/core/rtw_p2p.c
> > index 93d3c9c43..802e1170a 100644
> > --- a/drivers/staging/r8188eu/core/rtw_p2p.c
> > +++ b/drivers/staging/r8188eu/core/rtw_p2p.c
> > @@ -31,6 +31,8 @@ static u32 go_add_group_info_attr(struct wifidirect_info *pwdinfo, u8 *pbuf)
> >       struct sta_priv *pstapriv = &padapter->stapriv;
> >
> >       pdata_attr = kzalloc(MAX_P2P_IE_LEN, GFP_KERNEL);
> > +     if (!pdata_attr)
> > +             return 0;
>
> Return success here is not a good thing.  We have to fix the caller to
> check for errors.  (Fixing a bug half way just makes it harder to find
> the bug so it makes the situation worse).
>
> regards,
> dan carpenter
>