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* [PATCH] drm/i810: Prevent underflow in ioctl
@ 2019-10-04 10:22 ` Dan Carpenter
  0 siblings, 0 replies; 8+ messages in thread
From: Dan Carpenter @ 2019-10-04 10:22 UTC (permalink / raw)
  To: David Airlie
  Cc: kernel-janitors, linux-kernel, dri-devel, Sam Ravnborg,
	Emil Velikov

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;
 
 	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;
-- 
2.20.1

^ permalink raw reply related	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2019-10-04 16:05 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
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2019-10-04 10:22 [PATCH] drm/i810: Prevent underflow in ioctl Dan Carpenter
2019-10-04 10:22 ` Dan Carpenter
2019-10-04 10:22 ` Dan Carpenter
2019-10-04 14:08 ` Chris Wilson
2019-10-04 14:08   ` Chris Wilson
2019-10-04 16:04   ` Chris Wilson
2019-10-04 16:04     ` Chris Wilson
2019-10-04 16:04     ` Chris Wilson

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