dst: catch uninitialized metrics

Catch cases where dst_metric_set() and other functions are called
but _metrics is NULL.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/net/dst.h b/include/net/dst.h
index 07a0402c52e6..7d15d238b6ec 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -111,6 +111,8 @@ static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 {
         unsigned long p = dst->_metrics;
 
+        BUG_ON(!p);
+
         if (p & DST_METRICS_READ_ONLY)
                 return dst->ops->cow_metrics(dst, p);
         return __DST_METRICS_PTR(p);