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From cdd5c75a34654abb2516476b851c6730b4bcb11b Mon Sep 17 00:00:00 2001
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Message-Id: <cdd5c75a34654abb2516476b851c6730b4bcb11b@dist-git>
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From: Michal Privoznik <mprivozn@redhat.com>
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Date: Mon, 21 Jan 2019 09:04:11 -0500
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Subject: [PATCH] virrandom: Avoid undefined behaviour in virRandomBits
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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https://bugzilla.redhat.com/show_bug.cgi?id=1667329 (RHEL 7.6.z)
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https://bugzilla.redhat.com/show_bug.cgi?id=1652894 (RHEL 7.7)
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If nbits is 64 (or greater) then shifting 1ULL left is undefined.
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Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
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Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
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(cherry picked from commit 0a5a6f0d019996b015bb0acbe30efa8f2fbbb351)
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Signed-off-by: John Ferlan <jferlan@redhat.com>
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Message-Id: <20190121140412.27804-3-jferlan@redhat.com>
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Reviewed-by: Erik Skultety <eskultet@redhat.com>
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---
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src/util/virrandom.c | 4 +++-
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1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/src/util/virrandom.c b/src/util/virrandom.c
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index 3c011a8615..7915f6531e 100644
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--- a/src/util/virrandom.c
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+++ b/src/util/virrandom.c
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@@ -68,7 +68,9 @@ uint64_t virRandomBits(int nbits)
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return 0;
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}
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- ret &= (1ULL << nbits) - 1;
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+ if (nbits < 64)
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+ ret &= (1ULL << nbits) - 1;
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+
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return ret;
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}
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--
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2.20.1
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