Gentle ping. Apart from the spelling mistakes Sashiko already pointed out, any comments on that?
Regards, Christian. On 6/30/26 10:01, Christian König wrote: > We recently had another incident where two drivers put pages they got from > get_user_pages() into a DMA-buf and cause quite a number of problems. > > Explicitely document that this is not something exporters can do. > > Signed-off-by: Christian König <[email protected]> > --- > drivers/dma-buf/dma-buf.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > index 71f37544a5c6..aa5af4f439c2 100644 > --- a/drivers/dma-buf/dma-buf.c > +++ b/drivers/dma-buf/dma-buf.c > @@ -685,6 +685,14 @@ static struct file *dma_buf_getfile(size_t size, int > flags) > * > * For the detailed semantics exporters are expected to implement see > * &dma_buf_ops. > + * > + * It is explicitely forbidden for exporters to expose buffers they don't > "own" > + * as DMA-buf. This includes pages acquired by get_user_pages() or other > import > + * mechanism. Not following this rule can create numerous security problems. > + * > + * It is also strongly discouraged to expose the same backing store through > + * multiple DMA-bufs at the same time. This eventually creates aliasing and > + * cache coherency problems which are extremely hard to debug and fix. > */ > > /**
