linux-kernel - Re: [PATCH 2/2] hfsplus: add a check for hfs_bnode

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Message-ID: <CANhBUQ3vPBAstTMJ25Zt6sR4CcRKWkeR7VKhFXc9aiqQKmW=Ng@mail.gmail.com>
Date:   Thu, 17 Oct 2019 09:30:20 +0800
From:   Chuhong Yuan <hslester96@...il.com>
To:     Ernesto A. Fernández 
        <ernesto.mnd.fernandez@...il.com>
Cc:     linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] hfsplus: add a check for hfs_bnode_find

On Thu, Oct 17, 2019 at 8:07 AM Ernesto A. Fernández
<ernesto.mnd.fernandez@...il.com> wrote:
>
> Hi,
>
> On Wed, Oct 16, 2019 at 08:06:20PM +0800, Chuhong Yuan wrote:
> > hfs_brec_update_parent misses a check for hfs_bnode_find and may miss
> > the failure.
> > Add a check for it like what is done in again.
> >
> > Signed-off-by: Chuhong Yuan <hslester96@...il.com>
> > ---
> >  fs/hfsplus/brec.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/fs/hfsplus/brec.c b/fs/hfsplus/brec.c
> > index 1918544a7871..22bada8288c4 100644
> > --- a/fs/hfsplus/brec.c
> > +++ b/fs/hfsplus/brec.c
> > @@ -434,6 +434,8 @@ static int hfs_brec_update_parent(struct hfs_find_data *fd)
> >                       new_node->parent = tree->root;
> >               }
> >               fd->bnode = hfs_bnode_find(tree, new_node->parent);
> > +             if (IS_ERR(fd->bnode))
> > +                     return PTR_ERR(fd->bnode);
>
> You shouldn't just return here, you still hold a reference to new_node.
> The call to hfs_bnode_find() after the again label seems to be making a
> similar mistake.
>
> I don't think either one can actually fail though, because the parent
> nodes have all been read and hashed before, haven't they?
>

I find that after hfs_bnode_findhash in hfs_bnode_find, there is a test for
HFS_BNODE_ERROR and may return an error. I'm not sure whether it
can happen here.

> >               /* create index key and entry */
> >               hfs_bnode_read_key(new_node, fd->search_key, 14);
> >               cnid = cpu_to_be32(new_node->this);
> > --
> > 2.20.1
> >