On Wed, 24 Jan 2018, Laura Abbott wrote:
> On 01/22/2018 09:46 AM, Liam Mark wrote:
> > Since commit 204f672255c2 ("staging: android: ion: Use CMA APIs directly")
> > the CMA API is now used directly and therefore the allocated memory is no
> > longer automatically zeroed.
> >
> > Explicitly zero CMA allocated memory to ensure that no data is exposed to
> > userspace.
> >
> > Fixes: 204f672255c2 ("staging: android: ion: Use CMA APIs directly")
> > Signed-off-by: Liam Mark <lmark@xxxxxxxxxxxxxx>
> > ---
> > Changes in v2:
> > - Clean up the commit message.
> > - Add 'Fixes:'
> >
> > drivers/staging/android/ion/ion_cma_heap.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/staging/android/ion/ion_cma_heap.c
> > b/drivers/staging/android/ion/ion_cma_heap.c
> > index 86196ffd2faf..91a98785607a 100644
> > --- a/drivers/staging/android/ion/ion_cma_heap.c
> > +++ b/drivers/staging/android/ion/ion_cma_heap.c
> > @@ -51,6 +51,8 @@ static int ion_cma_allocate(struct ion_heap *heap, struct
> > ion_buffer *buffer,
> > if (!pages)
> > return -ENOMEM;
> >
> > + memset(page_address(pages), 0, size);
> > +
>
> This won't work for highmem pages. You need to zero by page via
> kmap_atomic in that case. You can use PageHighMem to separate the
> paths.
Thanks for catching that, I will update the patch.
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