3.2-stable review patch. If anyone has any objections, please let me know.
------------------ From: Tejun Heo <[email protected]> commit 201e72acb2d3821e2de9ce6091e98859c316b29a upstream. 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: Aristeu Rozanski <[email protected]> Cc: Li Zefan <[email protected]> [bwh: Backported to 3.2: - Adjust context - Exception list is called whitelist] Signed-off-by: Ben Hutchings <[email protected]> --- security/device_cgroup.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -202,8 +202,8 @@ static void devcgroup_destroy(struct cgr dev_cgroup = cgroup_to_devcgroup(cgroup); list_for_each_entry_safe(wh, tmp, &dev_cgroup->whitelist, list) { - list_del(&wh->list); - kfree(wh); + list_del_rcu(&wh->list); + kfree_rcu(wh, rcu); } kfree(dev_cgroup); } @@ -278,7 +278,7 @@ static int may_access_whitelist(struct d { struct dev_whitelist_item *whitem; - list_for_each_entry(whitem, &c->whitelist, list) { + list_for_each_entry_rcu(whitem, &c->whitelist, list) { if (whitem->type & DEV_ALL) return 1; if ((refwh->type & DEV_BLOCK) && !(whitem->type & DEV_BLOCK)) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
