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From:   Amir Goldstein <amir73il@gmail.com>
Date:   Thu, 12 Sep 2019 13:17:25 +0300
Message-ID: <CAOQ4uxjZefwTki=ojQuTT1RC8-ce+o=XZtzyUQ=0iFi6Q757Qg@mail.gmail.com>
Subject: Re: [PATCH V2] ovl: Fix dereferencing possible ERR_PTR()
To:     Miklos Szeredi <miklos@szeredi.hu>
Cc:     Ding Xiang <dingxiang@cmss.chinamobile.com>,
        overlayfs <linux-unionfs@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>
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On Thu, Sep 12, 2019 at 12:28 PM Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> On Thu, Sep 12, 2019 at 8:02 AM Amir Goldstein <amir73il@gmail.com> wrote:
> >
> > On Thu, Sep 12, 2019 at 8:24 AM Ding Xiang
> > <dingxiang@cmss.chinamobile.com> wrote:
> > >
> > > if ovl_encode_real_fh() fails, no memory was allocated
> > > and the error in the error-valued pointer should be returned.
> > >
> > > V1->V2: fix SHA1 length problem
> > >
> > > Fixes: 9b6faee07470 ("ovl: check ERR_PTR() return value from ovl_encode_fh()")
> > > Signed-off-by: Ding Xiang <dingxiang@cmss.chinamobile.com>
> > > ---
> > >  fs/overlayfs/export.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
> > > index cb8ec1f..50ade19 100644
> > > --- a/fs/overlayfs/export.c
> > > +++ b/fs/overlayfs/export.c
> > > @@ -229,7 +229,7 @@ static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
> > >                                 ovl_dentry_upper(dentry), !enc_lower);
> > >         err = PTR_ERR(fh);
> > >         if (IS_ERR(fh))
> > > -               goto fail;
> > > +               return err;
> > >
> >
> > Please fix the code in warning message instead of skipping the warning.
>
> Not sure that makes sense.   ovl_encode_real_fh() will either return
> -EIO in case of an internal error with WARN_ON() or it will return
> -ENOMEM on memory allocation failure, which doesn't warrant a debug
> message.
>

Very well. I did not look that deep.

No objections then.

Thanks,
Amir.