libvirt/SOURCES/libvirt-virrandom-Avoid-und...

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From 0a774bbd6c55f95a9cd106a0c79881a52b9cbdbc Mon Sep 17 00:00:00 2001
Message-Id: <0a774bbd6c55f95a9cd106a0c79881a52b9cbdbc@dist-git>
From: Michal Privoznik <mprivozn@redhat.com>
Date: Mon, 3 Dec 2018 08:46:19 -0500
Subject: [PATCH] virrandom: Avoid undefined behaviour in virRandomBits
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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https://bugzilla.redhat.com/show_bug.cgi?id=1655586 [RHEL8]
https://bugzilla.redhat.com/show_bug.cgi?id=1652894 [RHEL7]
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>
(cherry picked from commit 0a5a6f0d019996b015bb0acbe30efa8f2fbbb351)
Signed-off-by: John Ferlan <jferlan@redhat.com>
---
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;
}
--
2.20.1