[PATCH 4.9 090/109] dma-buf/sw-sync: Prevent user overflow on timeline advance

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>

commit 8f66d3aa1735bc95ae58d846a157357e8d41abb8 upstream.

The timeline is u32, which limits any single advance to INT_MAX so that
we can detect all fences that need signaling.

Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
Cc: Gustavo Padovan <gustavo@xxxxxxxxxxx>
Reviewed-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/20170629125930.821-3-chris@xxxxxxxxxxxxxxxxxx
[s/dma_fence/fence/g - gregkh]
Cc: Jisheng Zhang <Jisheng.Zhang@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/dma-buf/sw_sync.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/dma-buf/sw_sync.c
+++ b/drivers/dma-buf/sw_sync.c
@@ -345,6 +345,11 @@ static long sw_sync_ioctl_inc(struct syn
 	if (copy_from_user(&value, (void __user *)arg, sizeof(value)))
 		return -EFAULT;
 
+	while (value > INT_MAX)  {
+		sync_timeline_signal(obj, INT_MAX);
+		value -= INT_MAX;
+	}
+
 	sync_timeline_signal(obj, value);
 
 	return 0;