| From | Ben Hutchings <> | Date | Sat, 08 Feb 2020 18:19:18 +0000 | Subject | [PATCH 3.16 019/148] drm/i810: Prevent underflow in ioctl |
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3.16.82-rc1 review patch. If anyone has any objections, please let me know.
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From: Dan Carpenter <dan.carpenter@oracle.com>
commit 4f69851fbaa26b155330be35ce8ac393e93e7442 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 Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/gpu/drm/i810/i810_dma.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/i810/i810_dma.c +++ b/drivers/gpu/drm/i810/i810_dma.c @@ -724,7 +724,7 @@ static void i810_dma_dispatch_vertex(str 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) @@ -1044,7 +1044,7 @@ static void i810_dma_dispatch_mc(struct 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;
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