[libvirt] [PATCH] libvirt.c: don't let a NULL "cpumaps" argument provoke a NULL-deref

[Jim Meyering]

>From 94923b161a9d066146271bb533b78ab7877e4501 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering at redhat.com>
Date: Mon, 14 Dec 2009 17:17:53 +0100
Subject: [PATCH] libvirt.c: don't let a NULL "cpumaps" argument provoke a NULL-deref

* src/libvirt.c (virDomainGetVcpus): Update spec to say that maplen
is ignored when "cpumaps" is NULL.
Set maplen to 0 in that case.
---
 src/libvirt.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/src/libvirt.c b/src/libvirt.c
index 008e322..4325aa4 100644
--- a/src/libvirt.c
+++ b/src/libvirt.c
@@ -4753,6 +4753,7 @@ error:
  *      virDomainPinVcpu() API.
  * @maplen: number of bytes in one cpumap, from 1 up to size of CPU map in
  *	underlying virtualization system (Xen...).
+ *	Ignored when cpumaps is NULL.
  *
  * Extract information about virtual CPUs of domain, store it in info array
  * and also in cpumaps if this pointer isn't NULL.
@@ -4776,6 +4777,12 @@ virDomainGetVcpus(virDomainPtr domain, virVcpuInfoPtr info, int maxinfo,
         virLibDomainError(domain, VIR_ERR_INVALID_ARG, __FUNCTION__);
         goto error;
     }
+
+    /* Ensure that domainGetVcpus (aka remoteDomainGetVcpus) does not
+       try to memcpy anything into a NULL pointer.  */
+    if (cpumaps == NULL)
+        maplen = 0;
+
     if (cpumaps != NULL && maplen < 1) {
         virLibDomainError(domain, VIR_ERR_INVALID_ARG, __FUNCTION__);
         goto error;
--
1.6.6.rc2.275.g51e2d