Daniel P. Berrange wrote:
On Mon, Dec 14, 2009 at 05:18:54PM +0100, Jim Meyering wrote:
From 94923b161a9d066146271bb533b78ab7877e4501 Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyering@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; --
I wonder if it might be better to return an error in that case. Passing a NULL cpumaps, and non-zero maplen seems like a real application bug we should complain about
if (cpumaps == NULL && maplen != 0) ....error...
Either way is fine with me. I was trying to preserve what looked like existing intent. Let me know.