On Fri, 26 Nov 2021, Greg KH wrote:
> On Fri, Nov 26, 2021 at 08:56:27AM +0000, Lee Jones wrote:
> > On Fri, 26 Nov 2021, Dan Carpenter wrote:
> >
> > > On Thu, Nov 25, 2021 at 06:18:22PM +0300, Dan Carpenter wrote:
> > > > I had thought that ->kmap_cnt was a regular int and not an unsigned
> > > > int, but I would have to pull a stable tree to see where I misread the
> > > > code.
> > >
> > > I was looking at (struct ion_buffer)->kmap_cnt but this is
> > > (struct ion_handle)->kmap_cnt. I'm not sure how those are related but
> > > it makes me nervous that one can go higher than the other. Also both
> > > probably need overflow protection.
> > >
> > > So I guess I would just do something like:
> > >
> > > diff --git a/drivers/staging/android/ion/ion.c
> > > b/drivers/staging/android/ion/ion.c
> > > index 806e9b30b9dc8..e8846279b33b5 100644
> > > --- a/drivers/staging/android/ion/ion.c
> > > +++ b/drivers/staging/android/ion/ion.c
> > > @@ -489,6 +489,8 @@ static void *ion_buffer_kmap_get(struct ion_buffer
> > > *buffer)
> > > void *vaddr;
> > >
> > > if (buffer->kmap_cnt) {
> > > + if (buffer->kmap_cnt == INT_MAX)
> > > + return ERR_PTR(-EOVERFLOW);
> > > buffer->kmap_cnt++;
> > > return buffer->vaddr;
> > > }
> > > @@ -509,6 +511,8 @@ static void *ion_handle_kmap_get(struct ion_handle
> > > *handle)
> > > void *vaddr;
> > >
> > > if (handle->kmap_cnt) {
> > > + if (handle->kmap_cnt == INT_MAX)
> > > + return ERR_PTR(-EOVERFLOW);
> > > handle->kmap_cnt++;
> > > return buffer->vaddr;
> > > }
> >
> > Which is all well and good until somebody changes the type.
>
> That's hard to do on code that is removed from the kernel tree :)
That's a difficult stance to take when reviewing a patch which changes
the very code you base your argument on. :D
I'll do with Dan's PoV though - no sympathy given. :)
v3 to follow.
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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