[libvirt] [PATCH] Crash of libvirtd by unprivileged user in virConnectListAllInterfaces
From: "Daniel P. Berrange" <berrange@redhat.com> On Thu, Jun 27, 2013 at 03:56:42PM +0100, Daniel P. Berrange wrote:
Hi Security Team,
I've discovered a way for an unprivileged user with a readonly connection to libvirtd, to crash the daemon.
Ok, the final patch for this is issue will be the simpler variant that Eric suggested The embargo can be considered to be lifted on Monday July 1st, at 0900 UTC The following is the GIT change that DV or myself will apply to libvirt GIT master immediately before the 1.1.0 release:
From 177b4165c531a4b3ba7f6ab6aa41dca9ceb0b8cf Mon Sep 17 00:00:00 2001 From: "Daniel P. Berrange" <berrange@redhat.com> Date: Fri, 28 Jun 2013 10:48:37 +0100 Subject: [PATCH] CVE-2013-2218: Fix crash listing network interfaces with filters
The virConnectListAllInterfaces method has a double-free of the 'struct netcf_if' object when any of the filtering flags cause an interface to be skipped over. For example when running the command 'virsh iface-list --inactive' This is a regression introduced in release 1.0.6 by commit 7ac2c4fe624f30f2c8270116513fa2ddab07631f Author: Guannan Ren <gren@redhat.com> Date: Tue May 21 21:29:38 2013 +0800 interface: list all interfaces with flags == 0 Signed-off-by: Daniel P. Berrange <berrange@redhat.com> --- Posting as a courtesy FYI for anyone reading this list but who does not have access to the security list and doesn't want to crawl through git. This commit has been included in 1.1.0 and has been applied to all affected stable branches (just v1.0.6-maint). The rule in determining that a CVE was necessary is the "escalation of privilege" test - any time a read-only client can cause a denial-of-service against a more-privileged read-write client (by crashing libvirtd), there is an escalation. src/interface/interface_backend_netcf.c | 1 + 1 file changed, 1 insertion(+) diff --git a/src/interface/interface_backend_netcf.c b/src/interface/interface_backend_netcf.c index a995816..9aa673d 100644 --- a/src/interface/interface_backend_netcf.c +++ b/src/interface/interface_backend_netcf.c @@ -412,6 +412,7 @@ netcfConnectListAllInterfaces(virConnectPtr conn, (MATCH(VIR_CONNECT_LIST_INTERFACES_INACTIVE) && (status & NETCF_IFACE_INACTIVE)))) { ncf_if_free(iface); + iface = NULL; continue; } -- 1.8.1.4
On 07/02/2013 10:14 PM, Eric Blake wrote:
From: "Daniel P. Berrange" <berrange@redhat.com>
On Thu, Jun 27, 2013 at 03:56:42PM +0100, Daniel P. Berrange wrote:
Hi Security Team,
I've discovered a way for an unprivileged user with a readonly connection to libvirtd, to crash the daemon. Ok, the final patch for this is issue will be the simpler variant that Eric suggested
The embargo can be considered to be lifted on Monday July 1st, at 0900 UTC
The following is the GIT change that DV or myself will apply to libvirt GIT master immediately before the 1.1.0 release:
From 177b4165c531a4b3ba7f6ab6aa41dca9ceb0b8cf Mon Sep 17 00:00:00 2001 From: "Daniel P. Berrange" <berrange@redhat.com> Date: Fri, 28 Jun 2013 10:48:37 +0100 Subject: [PATCH] CVE-2013-2218: Fix crash listing network interfaces with filters
The virConnectListAllInterfaces method has a double-free of the 'struct netcf_if' object when any of the filtering flags cause an interface to be skipped over. For example when running the command 'virsh iface-list --inactive'
This is a regression introduced in release 1.0.6 by
commit 7ac2c4fe624f30f2c8270116513fa2ddab07631f Author: Guannan Ren <gren@redhat.com> Date: Tue May 21 21:29:38 2013 +0800
interface: list all interfaces with flags == 0
Signed-off-by: Daniel P. Berrange <berrange@redhat.com> ---
Posting as a courtesy FYI for anyone reading this list but who does not have access to the security list and doesn't want to crawl through git. This commit has been included in 1.1.0 and has been applied to all affected stable branches (just v1.0.6-maint).
The rule in determining that a CVE was necessary is the "escalation of privilege" test - any time a read-only client can cause a denial-of-service against a more-privileged read-write client (by crashing libvirtd), there is an escalation.
src/interface/interface_backend_netcf.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/src/interface/interface_backend_netcf.c b/src/interface/interface_backend_netcf.c index a995816..9aa673d 100644 --- a/src/interface/interface_backend_netcf.c +++ b/src/interface/interface_backend_netcf.c @@ -412,6 +412,7 @@ netcfConnectListAllInterfaces(virConnectPtr conn, (MATCH(VIR_CONNECT_LIST_INTERFACES_INACTIVE) && (status & NETCF_IFACE_INACTIVE)))) { ncf_if_free(iface); + iface = NULL; continue; }
Thanks for posting here. I have to say sorry about this bug I caused. This problem is caused by double-free 'iface' variable as Daniel pointed out when code path goes into cleanup label, there is a second ncf_if_free() for the variable if we didn't initialize it to NULL after the first ncf_if_free(). Guannan
participants (2)
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Eric Blake -
Guannan Ren