On Thursday, 13 December 2018 15:00:23 EET Sakari Ailus wrote:
> Hi Laurent,
>
> On Thu, Dec 13, 2018 at 02:57:46PM +0200, Laurent Pinchart wrote:
> > Hi Sakari,
> >
> > Thank you for the patch.
> >
> > On Thursday, 13 December 2018 12:40:05 EET Sakari Ailus wrote:
> > > buf->size is an unsigned long; casting that to int will lead to an
> > > overflow if buf->size exceeds INT_MAX.
> > >
> > > Fix this by changing the type to unsigned long instead. This is possible
> > > as the buf->size is always aligned to PAGE_SIZE, and therefore the size
> > > will never have values lesser than 0.
> >
> > This feels a bit fragile to me. We at least need a big comment in the code
> > to explain this. Another option would be a size -= min(..., size) just to
> > make sure.
>
> I was thinking of something like:
>
> if (WARN_ON(size & ~PAGE_MASK))
> return -ENOMEM;
>
> But I opted to writing the third patch as this is not the only place where
> the page alignment could be relevant.
>
> What do you think?
I'd do both :-)
> > > Note on backporting to stable: the file used to be under
> > > drivers/media/v4l2-core, it was moved to the current location after
> > > 4.14.
> > >
> > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > > Cc: stable@xxxxxxxxxxxxxxx
> > > ---
> > >
> > > drivers/media/common/videobuf2/videobuf2-dma-sg.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> > > b/drivers/media/common/videobuf2/videobuf2-dma-sg.c index
> > > 015e737095cdd..e9bfea986cc47 100644
> > > --- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> > > +++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> > > @@ -59,7 +59,7 @@ static int vb2_dma_sg_alloc_compacted(struct
> > > vb2_dma_sg_buf *buf, gfp_t gfp_flags)
> > >
> > > {
> > >
> > > unsigned int last_page = 0;
> > >
> > > - int size = buf->size;
> > > + unsigned long size = buf->size;
> > >
> > > while (size > 0) {
> > >
> > > struct page *pages;
--
Regards,
Laurent Pinchart
