[libvirt] [PATCH] Avoid libvirtd crash when cgroups is not configured on host

[Jim Fehlig <jfehlig@xxxxxxxxxx>]

Patch for libvirtd segfault discussed on IRC recently ...

Regards,
Jim


commit f034c0bfd7089ba3400b7a44b97540c4a8785e35
Author: Jim Fehlig <jfehlig@xxxxxxxxxx>
Date:   Sun Mar 21 19:59:13 2010 -0600

    Avoid libvirtd crash when cgroups is not configured on host
    
    Invoking virDomainSetMemory() on lxc driver results in libvirtd
    segfault when cgroups has not been configured on the host.
    
    Ensure driver->cgroup is non-null before invoking
    virCgroupForDomain().  To prevent similar segfaults in the future,
    ensure driver parameter to virCgroupForDomain() is non-null before
    dereferencing.

diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c
index aeec593..ba13065 100644
--- a/src/lxc/lxc_driver.c
+++ b/src/lxc/lxc_driver.c
@@ -625,6 +625,12 @@ static int lxcDomainSetMemory(virDomainPtr dom, unsigned long newmem) {
     }
 
     if (virDomainObjIsActive(vm)) {
+        if (driver->cgroup == NULL) {
+            lxcError(VIR_ERR_NO_SUPPORT,
+                     "%s", _("cgroups must be configured on the host"));
+            goto cleanup;
+        }
+
         if (virCgroupForDomain(driver->cgroup, vm->def->name, &cgroup, 0) != 0) {
             lxcError(VIR_ERR_INTERNAL_ERROR,
                      _("Unable to get cgroup for %s\n"), vm->def->name);
diff --git a/src/util/cgroup.c b/src/util/cgroup.c
index 8777781..496d9d3 100644
--- a/src/util/cgroup.c
+++ b/src/util/cgroup.c
@@ -692,6 +692,9 @@ int virCgroupForDomain(virCgroupPtr driver,
     int rc;
     char *path;
 
+    if (driver == NULL)
+        return -EINVAL;
+
     if (virAsprintf(&path, "%s/%s", driver->path, name) < 0)
         return -ENOMEM;
 

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