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drm/i810: Prevent underflow in ioctl 

commit 4f69851fba upstream.

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>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191004102251.GC823@mwanda
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Dan Carpenter 2019-10-04 13:22:51 +03:00 committed by Greg Kroah-Hartman
parent a77ab31626
commit 5d8115f535
1 changed files with 2 additions and 2 deletions
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4
drivers/gpu/drm/i810/i810_dma.c
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@ -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;