commit: 201e72acb2d3821e2de9ce6091e98859c316b29a From: Tejun Heo <[email protected]> Date: Tue, 6 Nov 2012 09:17:37 -0800 Subject: 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 <[email protected]> Acked-by: Serge E. Hallyn <[email protected]> Cc: [email protected] Cc: Aristeu Rozanski <[email protected]> Cc: Li Zefan <[email protected]> --- security/device_cgroup.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 96d87ea..b08d20c 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)) -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
