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. -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog