[PATCH] media: videobuf2: Fix integer overrun in allocation

[PATCH] media: videobuf2: Fix integer overrun in allocation

[Ricardo Ribalda]

The plane_length is an unsigned integer. So, if we have a size of
0xffffffff bytes we incorrectly allocate 0 bytes instead of 1 << 32.

Cc: stable@vger.kernel.org
Fixes: 7f8414594e47 ("[media] media: videobuf2: fix the length check for mmap")
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/common/videobuf2/videobuf2-core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 02281d13505f..543da515c761 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -223,8 +223,10 @@ static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
 	 * NOTE: mmapped areas should be page aligned
 	 */
 	for (plane = 0; plane < vb->num_planes; ++plane) {
+		unsigned long size = vb->planes[plane].length;
+
 		/* Memops alloc requires size to be page aligned. */
-		unsigned long size = PAGE_ALIGN(vb->planes[plane].length);
+		size = PAGE_ALIGN(size);
 
 		/* Did it wrap around? */
 		if (size < vb->planes[plane].length)
-- 
2.30.1.766.gb4fecdf3b7-goog

Re: [PATCH] media: videobuf2: Fix integer overrun in allocation

[Sergey Senozhatsky]

On (21/03/10 00:43), Ricardo Ribalda wrote:
> The plane_length is an unsigned integer. So, if we have a size of
> 0xffffffff bytes we incorrectly allocate 0 bytes instead of 1 << 32.

Hi Ricardo,

> @@ -223,8 +223,10 @@ static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
>  	 * NOTE: mmapped areas should be page aligned
>  	 */
>  	for (plane = 0; plane < vb->num_planes; ++plane) {
> +		unsigned long size = vb->planes[plane].length;
> +
>  		/* Memops alloc requires size to be page aligned. */
> -		unsigned long size = PAGE_ALIGN(vb->planes[plane].length);
> +		size = PAGE_ALIGN(size);
>  
>  		/* Did it wrap around? */
>  		if (size < vb->planes[plane].length)

Shouldn't the same be done in vb2_mmap()?

	-ss

Re: [PATCH] media: videobuf2: Fix integer overrun in allocation

[Ricardo Ribalda]

Hi Sergey

On Wed, Mar 10, 2021 at 2:42 AM Sergey Senozhatsky
<sergey.senozhatsky.work@gmail.com> wrote:
>
> On (21/03/10 00:43), Ricardo Ribalda wrote:
> > The plane_length is an unsigned integer. So, if we have a size of
> > 0xffffffff bytes we incorrectly allocate 0 bytes instead of 1 << 32.
>
> Hi Ricardo,
>
> > @@ -223,8 +223,10 @@ static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
> >        * NOTE: mmapped areas should be page aligned
> >        */
> >       for (plane = 0; plane < vb->num_planes; ++plane) {
> > +             unsigned long size = vb->planes[plane].length;
> > +
> >               /* Memops alloc requires size to be page aligned. */
> > -             unsigned long size = PAGE_ALIGN(vb->planes[plane].length);
> > +             size = PAGE_ALIGN(size);
> >
> >               /* Did it wrap around? */
> >               if (size < vb->planes[plane].length)
>
> Shouldn't the same be done in vb2_mmap()?
Indeed, I was having tunnel vision focussing on my issue.

I have sent a new patch.

Thanks!
>
>         -ss



--
Ricardo Ribalda

Re: [PATCH] media: videobuf2: Fix integer overrun in allocation

[Sergey Senozhatsky]

On (21/03/10 00:43), Ricardo Ribalda wrote:
> 
> The plane_length is an unsigned integer. So, if we have a size of
> 0xffffffff bytes we incorrectly allocate 0 bytes instead of 1 << 32.
> 
> Cc: stable@vger.kernel.org
> Fixes: 7f8414594e47 ("[media] media: videobuf2: fix the length check for mmap")
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>

Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>

Re: [PATCH] media: videobuf2: Fix integer overrun in allocation

[Laurent Pinchart]

Hi Ricardo,

Thank you for the patch.

On Wed, Mar 10, 2021 at 12:43:17AM +0100, Ricardo Ribalda wrote:
> The plane_length is an unsigned integer. So, if we have a size of
> 0xffffffff bytes we incorrectly allocate 0 bytes instead of 1 << 32.
> 
> Cc: stable@vger.kernel.org
> Fixes: 7f8414594e47 ("[media] media: videobuf2: fix the length check for mmap")
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/common/videobuf2/videobuf2-core.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> index 02281d13505f..543da515c761 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -223,8 +223,10 @@ static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
>  	 * NOTE: mmapped areas should be page aligned
>  	 */
>  	for (plane = 0; plane < vb->num_planes; ++plane) {
> +		unsigned long size = vb->planes[plane].length;

unsigned long is still 32-bit on 32-bit platforms.

> +
>  		/* Memops alloc requires size to be page aligned. */
> -		unsigned long size = PAGE_ALIGN(vb->planes[plane].length);
> +		size = PAGE_ALIGN(size);
>  
>  		/* Did it wrap around? */
>  		if (size < vb->planes[plane].length)

Doesn't this address the issue already ?


-- 
Regards,

Laurent Pinchart

Re: [PATCH] media: videobuf2: Fix integer overrun in allocation

[Ricardo Ribalda]

Hi Laurent

On Wed, Mar 10, 2021 at 8:49 AM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Ricardo,
>
> Thank you for the patch.
Thank you!
>
> On Wed, Mar 10, 2021 at 12:43:17AM +0100, Ricardo Ribalda wrote:
> > The plane_length is an unsigned integer. So, if we have a size of
> > 0xffffffff bytes we incorrectly allocate 0 bytes instead of 1 << 32.
> >
> > Cc: stable@vger.kernel.org
> > Fixes: 7f8414594e47 ("[media] media: videobuf2: fix the length check for mmap")
> > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > ---
> >  drivers/media/common/videobuf2/videobuf2-core.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> > index 02281d13505f..543da515c761 100644
> > --- a/drivers/media/common/videobuf2/videobuf2-core.c
> > +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> > @@ -223,8 +223,10 @@ static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
> >        * NOTE: mmapped areas should be page aligned
> >        */
> >       for (plane = 0; plane < vb->num_planes; ++plane) {
> > +             unsigned long size = vb->planes[plane].length;
>
> unsigned long is still 32-bit on 32-bit platforms.
>
> > +
> >               /* Memops alloc requires size to be page aligned. */
> > -             unsigned long size = PAGE_ALIGN(vb->planes[plane].length);
> > +             size = PAGE_ALIGN(size);
> >
> >               /* Did it wrap around? */
> >               if (size < vb->planes[plane].length)
>
> Doesn't this address the issue already ?

Yes and no. If you need to allocate 0xffffffff you are still affected
by the underrun. The core will return an error instead of doing the
allocation.

(yes, I know it is a lot of memory for a buffer)

>
>
> --
> Regards,
>
> Laurent Pinchart



-- 
Ricardo Ribalda

Re: [PATCH] media: videobuf2: Fix integer overrun in allocation

[Laurent Pinchart]

Hi Ricardo,

On Wed, Mar 10, 2021 at 08:58:39AM +0100, Ricardo Ribalda wrote:
> On Wed, Mar 10, 2021 at 8:49 AM Laurent Pinchart wrote:
> > On Wed, Mar 10, 2021 at 12:43:17AM +0100, Ricardo Ribalda wrote:
> > > The plane_length is an unsigned integer. So, if we have a size of
> > > 0xffffffff bytes we incorrectly allocate 0 bytes instead of 1 << 32.
> > >
> > > Cc: stable@vger.kernel.org
> > > Fixes: 7f8414594e47 ("[media] media: videobuf2: fix the length check for mmap")
> > > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > > ---
> > >  drivers/media/common/videobuf2/videobuf2-core.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> > > index 02281d13505f..543da515c761 100644
> > > --- a/drivers/media/common/videobuf2/videobuf2-core.c
> > > +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> > > @@ -223,8 +223,10 @@ static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
> > >        * NOTE: mmapped areas should be page aligned
> > >        */
> > >       for (plane = 0; plane < vb->num_planes; ++plane) {
> > > +             unsigned long size = vb->planes[plane].length;
> >
> > unsigned long is still 32-bit on 32-bit platforms.
> >
> > > +
> > >               /* Memops alloc requires size to be page aligned. */
> > > -             unsigned long size = PAGE_ALIGN(vb->planes[plane].length);
> > > +             size = PAGE_ALIGN(size);
> > >
> > >               /* Did it wrap around? */
> > >               if (size < vb->planes[plane].length)
> >
> > Doesn't this address the issue already ?
> 
> Yes and no. If you need to allocate 0xffffffff you are still affected
> by the underrun. The core will return an error instead of doing the
> allocation.
> 
> (yes, I know it is a lot of memory for a buffer)

That's my point, I don't think there's a need for this :-) Especially
with v4l2_buffer.m.offset being a __u32, we are limited to 4GB for *all*
buffers.

-- 
Regards,

Laurent Pinchart

Re: [PATCH] media: videobuf2: Fix integer overrun in allocation

[Ricardo Ribalda]

Hi Laurent

On Wed, Mar 10, 2021 at 9:12 AM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Ricardo,
>
> On Wed, Mar 10, 2021 at 08:58:39AM +0100, Ricardo Ribalda wrote:
> > On Wed, Mar 10, 2021 at 8:49 AM Laurent Pinchart wrote:
> > > On Wed, Mar 10, 2021 at 12:43:17AM +0100, Ricardo Ribalda wrote:
> > > > The plane_length is an unsigned integer. So, if we have a size of
> > > > 0xffffffff bytes we incorrectly allocate 0 bytes instead of 1 << 32.
> > > >
> > > > Cc: stable@vger.kernel.org
> > > > Fixes: 7f8414594e47 ("[media] media: videobuf2: fix the length check for mmap")
> > > > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > > > ---
> > > >  drivers/media/common/videobuf2/videobuf2-core.c | 4 +++-
> > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> > > > index 02281d13505f..543da515c761 100644
> > > > --- a/drivers/media/common/videobuf2/videobuf2-core.c
> > > > +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> > > > @@ -223,8 +223,10 @@ static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
> > > >        * NOTE: mmapped areas should be page aligned
> > > >        */
> > > >       for (plane = 0; plane < vb->num_planes; ++plane) {
> > > > +             unsigned long size = vb->planes[plane].length;
> > >
> > > unsigned long is still 32-bit on 32-bit platforms.
> > >
> > > > +
> > > >               /* Memops alloc requires size to be page aligned. */
> > > > -             unsigned long size = PAGE_ALIGN(vb->planes[plane].length);
> > > > +             size = PAGE_ALIGN(size);
> > > >
> > > >               /* Did it wrap around? */
> > > >               if (size < vb->planes[plane].length)
> > >
> > > Doesn't this address the issue already ?
> >
> > Yes and no. If you need to allocate 0xffffffff you are still affected
> > by the underrun. The core will return an error instead of doing the
> > allocation.
> >
> > (yes, I know it is a lot of memory for a buffer)
>
> That's my point, I don't think there's a need for this :-) Especially
> with v4l2_buffer.m.offset being a __u32, we are limited to 4GB for *all*
> buffers.

I guess I will convert this patch into a documentation patch, so we
explicitly know the limit of the API
(1<<32 - PAGE_SIZE).

Thanks!

>
> --
> Regards,
>
> Laurent Pinchart



-- 
Ricardo Ribalda