[libvirt] [PATCH] audit: eliminate potential null pointer deref when auditing macvtap devices

[Eric Blake]

On 03/14/2011 09:18 AM, Laine Stump wrote:
> The newly added call to qemuAuditNetDevice in qemuPhysIfaceConnect was
> assuming that res_ifname (the name of the macvtap device) was always
> valid, but this isn't the case. If openMacvtapTap fails, it always
> returns NULL, which would result in a segv.
> 
> Since the audit log only needs a record of devices that are actually
> sent to qemu, and a failure to open the macvtap device means that no
> device will be sent to qemu, we can solve this problem by only doing
> the audit if openMacvtapTap is successful (in which case res_ifname is
> guaranteed valid).
> ---
>  src/qemu/qemu_command.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index 8ca656a..72f55d0 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -128,8 +128,8 @@ qemuPhysIfaceConnect(virDomainDefPtr def,
>                          net->data.direct.mode, vnet_hdr, def->uuid,
>                          &net->data.direct.virtPortProfile, &res_ifname,
>                          vmop);
> -    qemuAuditNetDevice(def, net, res_ifname, rc >= 0);
>      if (rc >= 0) {
> +        qemuAuditNetDevice(def, net, res_ifname, true);
>          VIR_FREE(net->ifname);
>          net->ifname = res_ifname;
>      }

ACK.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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