linux-kernel - Re: [PATCH] tee/tee_shm.c: Fix error handling path

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Message-ID: <CAFqt6zb3=JgD0FPwj9=RNvHRVEQF_fCvaH10eSidwZryTOMZ5A@mail.gmail.com>
Date:   Mon, 14 Sep 2020 07:09:36 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     Jens Wiklander <jens.wiklander@...aro.org>
Cc:     op-tee@...ts.trustedfirmware.org, linux-kernel@...r.kernel.org,
        John Hubbard <jhubbard@...dia.com>
Subject: Re: [PATCH] tee/tee_shm.c: Fix error handling path

On Mon, Sep 14, 2020 at 1:59 AM Jens Wiklander
<jens.wiklander@...aro.org> wrote:
>
> On Sun, Sep 13, 2020 at 10:12:11AM +0530, Souptick Joarder wrote:
> > When shm->num_pages <= 0, we should avoid calling
> > release_registered_pages() in error handling path.
> What are we fixing?

Current code is working fine and this patch is not needed. Sorry for the noise.
>
> >
> > Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
> > Cc: John Hubbard <jhubbard@...dia.com>
> > ---
> >  drivers/tee/tee_shm.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> > index 00472f5..e517d9f 100644
> > --- a/drivers/tee/tee_shm.c
> > +++ b/drivers/tee/tee_shm.c
> > @@ -260,8 +260,7 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> >               rc = get_kernel_pages(kiov, num_pages, 0, shm->pages);
> >               kfree(kiov);
> >       }
> > -     if (rc > 0)
> > -             shm->num_pages = rc;
> > +     shm->num_pages = rc;
> Why not avoiding assigning invalid values to shm->num_pages?
> By the way, shm->num_pages is a size_t.
>
> >       if (rc != num_pages) {
> >               if (rc >= 0)
> >                       rc = -ENOMEM;
> > @@ -309,7 +308,9 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> >                       idr_remove(&teedev->idr, shm->id);
> >                       mutex_unlock(&teedev->mutex);
> >               }
> > -             release_registered_pages(shm);
> > +             if (shm->pages && (shm->num_pages > 0))
> > +                     release_registered_pages(shm);
> > +
> With this we'll leak if shm->pages has been assigned something.
>
> >       }
> >       kfree(shm);
> >       teedev_ctx_put(ctx);
> > -