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authorTejun Heo <tj@kernel.org>2012-11-06 09:17:37 -0800
committerTejun Heo <tj@kernel.org>2012-11-06 12:25:51 -0800
commit201e72acb2d3821e2de9ce6091e98859c316b29a (patch)
tree01e47038346474d659714151b8209673c11f330a /security
parent64e104771351d365e51e588a0e9a656ae6ed2f50 (diff)
downloadlinux-201e72acb2d3821e2de9ce6091e98859c316b29a.tar.gz
device_cgroup: fix RCU usage
dev_cgroup->exceptions is protected with devcgroup_mutex for writes and RCU for reads; however, RCU usage isn't correct. * dev_exception_clean() doesn't use RCU variant of list_del() and kfree(). The function can race with may_access() and may_access() may end up dereferencing already freed memory. Use list_del_rcu() and kfree_rcu() instead. * may_access() may be called only with RCU read locked but doesn't use RCU safe traversal over ->exceptions. Use list_for_each_entry_rcu(). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Cc: stable@vger.kernel.org Cc: Aristeu Rozanski <aris@redhat.com> Cc: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'security')
-rw-r--r--security/device_cgroup.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 96d87eab166..b08d20c66c2 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -164,8 +164,8 @@ static void dev_exception_clean(struct dev_cgroup *dev_cgroup)
struct dev_exception_item *ex, *tmp;
list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) {
- list_del(&ex->list);
- kfree(ex);
+ list_del_rcu(&ex->list);
+ kfree_rcu(ex, rcu);
}
}
@@ -298,7 +298,7 @@ static int may_access(struct dev_cgroup *dev_cgroup,
struct dev_exception_item *ex;
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))
continue;
if ((refex->type & DEV_CHAR) && !(ex->type & DEV_CHAR))