[PATCH 3/7] dma-buf/sw-sync: Prevent user overflow on timeline advance

[Chris Wilson]

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 at chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal at linaro.org>
Cc: Sean Paul <seanpaul at chromium.org>
Cc: Gustavo Padovan <gustavo at padovan.org>
---
 drivers/dma-buf/sw_sync.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c
index 4d5d8c5e2534..0e676d08aa70 100644
--- 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 sync_timeline *obj, unsigned long arg)
 	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;
-- 
2.13.1