linux-kernel - Re: [PATCH] udf: fix an uninitialized read bug

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Message-ID: <CAAa=b7ck+vDHr1iG6R2zX0NEpkEVOTGKqQVYhFR4xPOwn-C+hg@mail.gmail.com>
Date:   Mon, 15 Apr 2019 12:34:54 -0500
From:   Wenwen Wang <wang6495@....edu>
To:     Jan Kara <jack@...e.cz>
Cc:     Jan Kara <jack@...e.com>, open list <linux-kernel@...r.kernel.org>,
        Wenwen Wang <wang6495@....edu>
Subject: Re: [PATCH] udf: fix an uninitialized read bug

Thanks for your prompt reply, Jan! I will rework the patch.

Best regards,
Wenwen

On Mon, Apr 15, 2019 at 11:05 AM Jan Kara <jack@...e.cz> wrote:
>
> On Mon 15-04-19 10:26:24, Wenwen Wang wrote:
> > In udf_lookup(), the pointer 'fi' is a local variable initialized by the
> > return value of the function call udf_find_entry(). However, if the macro
> > 'UDF_RECOVERY' is defined, this variable will become uninitialized if the
> > else branch is not taken, which can potentially cause incorrect results in
> > the following execution.
> >
> > This patch simply initializes this local pointer to NULL.
> >
> > Signed-off-by: Wenwen Wang <wang6495@....edu>
>
> Thanks for the patch! A better fix is to drop the whole UDF_RECOVERY ifdef
> and what's in it. It is just dead code anyway.
>
>                                                                 Honza
>
> > ---
> >  fs/udf/namei.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/udf/namei.c b/fs/udf/namei.c
> > index 58cc241..9d499e1 100644
> > --- a/fs/udf/namei.c
> > +++ b/fs/udf/namei.c
> > @@ -299,7 +299,7 @@ static struct dentry *udf_lookup(struct inode *dir, struct dentry *dentry,
> >       struct inode *inode = NULL;
> >       struct fileIdentDesc cfi;
> >       struct udf_fileident_bh fibh;
> > -     struct fileIdentDesc *fi;
> > +     struct fileIdentDesc *fi = NULL;
> >
> >       if (dentry->d_name.len > UDF_NAME_LEN)
> >               return ERR_PTR(-ENAMETOOLONG);
> > --
> > 2.7.4
> >
> >
> --
> Jan Kara <jack@...e.com>
> SUSE Labs, CR