Re: CVS commit: src/sys

[Rin Okuyama <rokuyama.rk%gmail.com@localhost>]

Ah, you are right. We leaks uninitialized memory via mmap.

However, I'm not sure that it is safe to write DMA buffer
above sc->sc_vramsize after bus_dmamap_load?

Thoughts, ARM experts?

Thanks,
rin

On 2019/07/24 0:22, maya%netbsd.org@localhost wrote:
> I think we might be leaking uninitialized kernel memory.
>
> in tifb,
>
>          if (bus_dmamem_alloc(sc->sc_dmat, sc->sc_vramsize, 0, 0,
>              sc->sc_dmamem, 1, &segs, BUS_DMA_NOWAIT) != 0) {
>
> bus_dma* rounds up to PAGE_SIZE chunks.
>
>          memset((void *)sc->sc_vramaddr, 0, sc->sc_vramsize);
>
> We zero the not-rounded-up size.
>
> What do you think?
>
> On Tue, Jul 23, 2019 at 02:34:12PM +0000, Rin Okuyama wrote:
> > Module Name:	src
> > Committed By:	rin
> > Date:		Tue Jul 23 14:34:12 UTC 2019
> >
> > Modified Files:
> > 	src/sys/arch/arm/omap: tifb.c
> > 	src/sys/arch/luna68k/dev: lunafb.c
> > 	src/sys/dev/fdt: simplefb.c
> >
> > Log Message:
> > For drivers whose framebuffer is located not page-aligned, permit
> > offset of mmap up to (length of framebuffer) + (page offset of base
> > address of framebuffer). This is necessary in order to map the
> > highest page of framebuffer correctly, see,
> > http://cvsweb.netbsd.org/bsdweb.cgi/xsrc/external/mit/xf86-video-wsfb/dist/src/wsfb_driver.c#rev1.35