2020-09-13 04:45:33

by Souptick Joarder

Subject: [PATCH] tee/tee_shm.c: Fix error handling path

When shm->num_pages <= 0, we should avoid calling
release_registered_pages() in error handling path.

Signed-off-by: Souptick Joarder <[email protected]>
Cc: John Hubbard <[email protected]>
---
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;
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);
+
}
kfree(shm);
teedev_ctx_put(ctx);
--
1.9.1

2020-09-13 13:04:31

by Souptick Joarder

Subject: Re: [PATCH] tee/tee_shm.c: Fix error handling path

On Sun, Sep 13, 2020 at 2:00 PM Markus Elfring <[email protected]> wrote:
>
> > When shm->num_pages <= 0, we should avoid calling
> > release_registered_pages() in error handling path.
>
> * Would an imperative wording become helpful for the change description?
>
> * I suggest to add the tag “Fixes” to the commit message.

Sure. Will address both in v2.
>
> Regards,
> Markus

2020-09-13 20:32:04

by Jens Wiklander

Subject: Re: [PATCH] tee/tee_shm.c: Fix error handling path

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?

>
> Signed-off-by: Souptick Joarder <[email protected]>
> Cc: John Hubbard <[email protected]>
> ---
> 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);
> --
> 1.9.1
>

Thanks,
Jens

2020-09-14 01:44:10

by Souptick Joarder

Subject: Re: [PATCH] tee/tee_shm.c: Fix error handling path

On Mon, Sep 14, 2020 at 1:59 AM Jens Wiklander
<[email protected]> 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 <[email protected]>
> > Cc: John Hubbard <[email protected]>
> > ---
> > 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);
> > -