2019-12-04 14:13:06

by Colin King

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

From: Colin Ian King <[email protected]>

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 <[email protected]>
---
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

2019-12-05 02:39:48

by Kevin Hilman

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

Colin King <[email protected]> writes:

> From: Colin Ian King <[email protected]>
>
> 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 <[email protected]>

Reviewed-by: Kevin Hilman <[email protected]>

2019-12-05 08:07:00

by Sergey Senozhatsky

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

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

2019-12-13 07:48:40

by Maxime Jourdan

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

On Thu, Dec 5, 2019 at 9:06 AM Sergey Senozhatsky
<[email protected]> 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.