virrandom: Avoid undefined behaviour in virRandomBits

If nbits is 64 (or greater) then shifting 1ULL left is undefined.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

diff --git a/src/util/virrandom.c b/src/util/virrandom.c
index 3c011a861501397172d495a0ebdc453f1bfbd55c..7915f6531e2965b0f3de752e970083007bab5ead 100644 (file)
--- a/src/util/virrandom.c
+++ b/src/util/virrandom.c
@@ -68,7 +68,9 @@ uint64_t virRandomBits(int nbits)
         return 0;
     }
 
-    ret &= (1ULL << nbits) - 1;
+    if (nbits < 64)
+        ret &= (1ULL << nbits) - 1;
+
     return ret;
 }