From 14781719b38ba33f8870eb9d5ef9e3cdb7d40116 Mon Sep 17 00:00:00 2001 Message-Id: <14781719b38ba33f8870eb9d5ef9e3cdb7d40116@dist-git> From: Michal Privoznik Date: Mon, 21 Jan 2019 09:04:11 -0500 Subject: [PATCH] virrandom: Avoid undefined behaviour in virRandomBits MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit https://bugzilla.redhat.com/show_bug.cgi?id=1667329 (RHEL 7.6.z) https://bugzilla.redhat.com/show_bug.cgi?id=1652894 (RHEL 7.7) If nbits is 64 (or greater) then shifting 1ULL left is undefined. Signed-off-by: Michal Privoznik Reviewed-by: Daniel P. Berrangé (cherry picked from commit 0a5a6f0d019996b015bb0acbe30efa8f2fbbb351) Signed-off-by: John Ferlan Message-Id: <20190121140412.27804-3-jferlan@redhat.com> Reviewed-by: Erik Skultety --- src/util/virrandom.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) 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; } -- 2.21.0