linux-kernel - Re: [PATCH] fs/bfs: Null check to prevent null-ptr-deref bug

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Message-ID: <CAK+_RL=C2u07fL+OS7nW5bx1KR=-_wTfECi0e8xBtvxoF_czpw@mail.gmail.com>
Date: Sun, 7 Jan 2024 15:23:32 +0000
From: Tigran Aivazian <aivazian.tigran@...il.com>
To: "Christian A. Ehrhardt" <lk@...e.de>
Cc: Xiaochen Zou <xzou017@....edu>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fs/bfs: Null check to prevent null-ptr-deref bug

Hi,

On Sat, 6 Jan 2024 at 18:54, Christian A. Ehrhardt <lk@...e.de> wrote:
> > >         if (!bh)
> > >                 return -EIO;
> > >         new = sb_getblk(sb, to);
> > > +       if (unlikely(!new))
> > > +               return -ENOMEM;
>
> What's with the bh in this case? Wouldn't we need a brelse or something?

Oh sorry, mea culpa et senecta :) Since the data has been read into bh
then I suppose we need bforget(bh) rather than brelse(bh) before
returning -ENOMEM above.

Kind regards,
Tigran