From: Michal Privoznik <mprivozn@redhat.com>
Date: Thu, 2 Aug 2018 07:29:38 +0000 (+0200)
Subject: virrandom: Avoid undefined behaviour in virRandomBits
X-Git-Tag: v4.7.0-rc1~320
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0a5a6f0d019996b015bb0acbe30efa8f2fbbb351;p=thirdparty%2Flibvirt.git

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 3c011a8615..7915f6531e 100644
--- 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;
 }