From 96403da244443d9842dbf290c2a02390b78a158e Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Thu, 23 Jan 2014 15:53:01 -0800 Subject: [PATCH] memcg: fix possible NULL deref while traversing memcg_slab_caches list All caches of the same memory cgroup are linked in the memcg_slab_caches list via kmem_cache::memcg_params::list. This list is traversed, for example, when we read memory.kmem.slabinfo. Since the list actually consists of memcg_cache_params objects, we have to convert an element of the list to a kmem_cache object using memcg_params_to_cache(), which obtains the pointer to the cache from the memcg_params::memcg_caches array of the corresponding root cache. That said the pointer to a kmem_cache in its parent's memcg_params must be initialized before adding the cache to the list, and cleared only after it has been unlinked. Currently it is vice-versa, which can result in a NULL ptr dereference while traversing the memcg_slab_caches list. This patch restores the correct order. Signed-off-by: Vladimir Davydov Cc: Michal Hocko Cc: Glauber Costa Cc: Johannes Weiner Cc: Balbir Singh Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-format-patch failed