On 08/22/2018 10:54 AM, Daniel Vetter wrote:
DRM drivers really, really, really don't want random userspace to
share buffer behind it's back, bypassing the dma-buf buffer sharing
machanism. For that reason we've ruthlessly rejected any IOCTL
exposing the physical address of any graphics buffer.
Unfortunately fbdev comes with that built-in. We could just set
smem_start to 0, but that means we'd have to hand-roll our own fb_mmap
implementation. For good reasons many drivers do that, but
smem_start/length is still super convenient.
Hence instead just stop the leak in the ioctl, to keep fb mmap working
as-is. A second patch will set this flag for all drm drivers.
Cc: Bartlomiej Zolnierkiewicz <redacted>
Cc: Kees Cook <redacted>
Cc: Daniel Vetter <redacted>
Cc: <redacted>
Signed-off-by: Daniel Vetter <redacted>
Acked-by: Bartlomiej Zolnierkiewicz <redacted>
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics