Quoting Dan Carpenter (2019-10-04 11:22:51) > The "used" variables here come from the user in the ioctl and it can be > negative. It could result in an out of bounds write. > > Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> > --- > drivers/gpu/drm/i810/i810_dma.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i810/i810_dma.c b/drivers/gpu/drm/i810/i810_dma.c > index 2a77823b8e9a..e66c38332df4 100644 > --- a/drivers/gpu/drm/i810/i810_dma.c > +++ b/drivers/gpu/drm/i810/i810_dma.c > @@ -728,7 +728,7 @@ static void i810_dma_dispatch_vertex(struct drm_device *dev, > if (nbox > I810_NR_SAREA_CLIPRECTS) > nbox = I810_NR_SAREA_CLIPRECTS; > > - if (used > 4 * 1024) > + if (used < 0 || used > 4 * 1024) > used = 0; Yes, as passed to the GPU instruction, negative used is invalid. Then it is used as an offset into a memblock, where a negative offset would be very bad. Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> -Chris
