| Message ID | 20191004102251.GC823@mwanda (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i810: Prevent underflow in ioctl | expand |
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@oracle.com> > --- > 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@chris-wilson.co.uk> -Chris
Quoting Chris Wilson (2019-10-04 15:08:57) > 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@oracle.com> > > --- > > 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@chris-wilson.co.uk> Applied to drm-misc-next with cc'ed stable. -Chris
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; if (sarea_priv->dirty) @@ -1048,7 +1048,7 @@ static void i810_dma_dispatch_mc(struct drm_device *dev, struct drm_buf *buf, in if (u != I810_BUF_CLIENT) DRM_DEBUG("MC found buffer that isn't mine!\n"); - if (used > 4 * 1024) + if (used < 0 || used > 4 * 1024) used = 0; sarea_priv->dirty = 0x7f;
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@oracle.com> --- drivers/gpu/drm/i810/i810_dma.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)