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Merge branch 'for-3.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 

Pull cgroup fixes from Tejun Heo:
 "This contains two fix patches for device_cgroup.  One fixes a
  regression introduced earlier in 3.7 cycle where device_cgroup could
  try to dereference the NULL parent of the root cgroup.  The other one
  is RCU usage fix."

* 'for-3.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  device_cgroup: fix RCU usage
  device_cgroup: fix unchecked cgroup parent usage
This commit is contained in:
Linus Torvalds 2012-11-14 13:44:04 -08:00
parent 9924a1992a 201e72acb2
commit 1e096209da
1 changed files with 13 additions and 5 deletions
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18
security/device_cgroup.c
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@ -164,8 +164,8 @@ static void dev_exception_clean(struct dev_cgroup *dev_cgroup)
struct dev_exception_item *ex, *tmp; struct dev_exception_item *ex, *tmp;
list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) { list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) {
list_del(&ex->list); list_del_rcu(&ex->list);
kfree(ex); kfree_rcu(ex, rcu);
} }
} }
@ -298,7 +298,7 @@ static int may_access(struct dev_cgroup *dev_cgroup,
struct dev_exception_item *ex; struct dev_exception_item *ex;
bool match = false; bool match = false;
list_for_each_entry(ex, &dev_cgroup->exceptions, list) { list_for_each_entry_rcu(ex, &dev_cgroup->exceptions, list) {
if ((refex->type & DEV_BLOCK) && !(ex->type & DEV_BLOCK)) if ((refex->type & DEV_BLOCK) && !(ex->type & DEV_BLOCK))
continue; continue;
if ((refex->type & DEV_CHAR) && !(ex->type & DEV_CHAR)) if ((refex->type & DEV_CHAR) && !(ex->type & DEV_CHAR))
@ -352,6 +352,8 @@ static int parent_has_perm(struct dev_cgroup *childcg,
*/ */
static inline int may_allow_all(struct dev_cgroup *parent) static inline int may_allow_all(struct dev_cgroup *parent)
{ {
if (!parent)
return 1;
return parent->behavior == DEVCG_DEFAULT_ALLOW; return parent->behavior == DEVCG_DEFAULT_ALLOW;
} }
@ -376,11 +378,14 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
int count, rc; int count, rc;
struct dev_exception_item ex; struct dev_exception_item ex;
struct cgroup *p = devcgroup->css.cgroup; struct cgroup *p = devcgroup->css.cgroup;
struct dev_cgroup *parent = cgroup_to_devcgroup(p->parent); struct dev_cgroup *parent = NULL;
if (!capable(CAP_SYS_ADMIN)) if (!capable(CAP_SYS_ADMIN))
return -EPERM; return -EPERM;
if (p->parent)
parent = cgroup_to_devcgroup(p->parent);
memset(&ex, 0, sizeof(ex)); memset(&ex, 0, sizeof(ex));
b = buffer; b = buffer;
@ -391,11 +396,14 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
if (!may_allow_all(parent)) if (!may_allow_all(parent))
return -EPERM; return -EPERM;
dev_exception_clean(devcgroup); dev_exception_clean(devcgroup);
devcgroup->behavior = DEVCG_DEFAULT_ALLOW;
if (!parent)
break;
rc = dev_exceptions_copy(&devcgroup->exceptions, rc = dev_exceptions_copy(&devcgroup->exceptions,
&parent->exceptions); &parent->exceptions);
if (rc) if (rc)
return rc; return rc;
devcgroup->behavior = DEVCG_DEFAULT_ALLOW;
break; break;
case DEVCG_DENY: case DEVCG_DENY:
dev_exception_clean(devcgroup); dev_exception_clean(devcgroup);