dma-buf/sw-sync: Prevent user overflow on timeline advance

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@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170629125930.821-3-chris@chris-wilson.co.uk

1 files changed, 5 insertions, 0 deletions

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;