[PATCH] media: meson: add missing allocation failure check on new_buf

[PATCH] media: meson: add missing allocation failure check on new_buf

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Currently if the allocation of new_buf fails then a null pointer
dereference occurs when assiging new_buf->vb. Avoid this by returning
early on a memory allocation failure as there is not much more can
be done at this point.

Addresses-Coverity: ("Dereference null return")
Fixes: 3e7f51bd9607 ("media: meson: add v4l2 m2m video decoder driver")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/staging/media/meson/vdec/vdec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/staging/media/meson/vdec/vdec.c b/drivers/staging/media/meson/vdec/vdec.c
index 0a1a04fd5d13..8dd1396909d7 100644
--- a/drivers/staging/media/meson/vdec/vdec.c
+++ b/drivers/staging/media/meson/vdec/vdec.c
@@ -133,6 +133,8 @@ vdec_queue_recycle(struct amvdec_session *sess, struct vb2_buffer *vb)
 	struct amvdec_buffer *new_buf;
 
 	new_buf = kmalloc(sizeof(*new_buf), GFP_KERNEL);
+	if (!new_buf)
+		return;
 	new_buf->vb = vb;
 
 	mutex_lock(&sess->bufs_recycle_lock);
-- 
2.24.0

Re: [PATCH] media: meson: add missing allocation failure check on new_buf

[Kevin Hilman]

Colin King <colin.king@canonical.com> writes:

> From: Colin Ian King <colin.king@canonical.com>
>
> Currently if the allocation of new_buf fails then a null pointer
> dereference occurs when assiging new_buf->vb. Avoid this by returning
> early on a memory allocation failure as there is not much more can
> be done at this point.
>
> Addresses-Coverity: ("Dereference null return")
> Fixes: 3e7f51bd9607 ("media: meson: add v4l2 m2m video decoder driver")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Reviewed-by: Kevin Hilman <khilman@baylibre.com>

Re: [PATCH] media: meson: add missing allocation failure check on new_buf

[Sergey Senozhatsky]

On (19/12/04 14:11), Colin King wrote:
[..]
> diff --git a/drivers/staging/media/meson/vdec/vdec.c b/drivers/staging/media/meson/vdec/vdec.c
> index 0a1a04fd5d13..8dd1396909d7 100644
> --- a/drivers/staging/media/meson/vdec/vdec.c
> +++ b/drivers/staging/media/meson/vdec/vdec.c
> @@ -133,6 +133,8 @@ vdec_queue_recycle(struct amvdec_session *sess, struct vb2_buffer *vb)
>  	struct amvdec_buffer *new_buf;
>
>  	new_buf = kmalloc(sizeof(*new_buf), GFP_KERNEL);
> +	if (!new_buf)
> +		return;
>  	new_buf->vb = vb;

So the buffer is not getting recycled? IOW is leaked?

	-ss

Re: [PATCH] media: meson: add missing allocation failure check on new_buf

[Maxime Jourdan]

On Thu, Dec 5, 2019 at 9:06 AM Sergey Senozhatsky
<sergey.senozhatsky.work@gmail.com> wrote:
>
> On (19/12/04 14:11), Colin King wrote:
> [..]
> > diff --git a/drivers/staging/media/meson/vdec/vdec.c b/drivers/staging/media/meson/vdec/vdec.c
> > index 0a1a04fd5d13..8dd1396909d7 100644
> > --- a/drivers/staging/media/meson/vdec/vdec.c
> > +++ b/drivers/staging/media/meson/vdec/vdec.c
> > @@ -133,6 +133,8 @@ vdec_queue_recycle(struct amvdec_session *sess, struct vb2_buffer *vb)
> >       struct amvdec_buffer *new_buf;
> >
> >       new_buf = kmalloc(sizeof(*new_buf), GFP_KERNEL);
> > +     if (!new_buf)
> > +             return;
> >       new_buf->vb = vb;

Thanks for the patch Colin.

>
> So the buffer is not getting recycled? IOW is leaked?
>
>         -ss

The "recycle" mechanism in the meson vdec is a way to tell the
firmware that "hey, both userspace and kernel are done using this
buffer, you can start using it again".

Not queuing it for recycling means that the firmware won't use this
buffer again, it's not desirable of course, but if there is no memory
left to allocate a simple list element then there are bigger problems
at hand.

Either way, failing this allocation and returning instantly doesn't
leak anything or do any damage kernel-side.