From: Li Zefan Subject: [PATCH 7/8] cgroup: fix an almost harmless off-by-one bug Date: Tue, 12 Mar 2013 14:52:15 +0800 Message-ID: <513ED09F.2020906@huawei.com> References: <513ED010.5060906@huawei.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <513ED010.5060906-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Tejun Heo Cc: LKML , Cgroups The 3rd parameter of flex_array_prealloc() is the number of elements, not the index of the last element. The effect of the bug is, when opening cgroup.procs, a flex array will be allocated and all elements of the array is allocated with GFP_KERNEL flag, but the last one is GFP_ATOMIC, , and if we fail to allocate memory for it, it'll trigger a BUG_ON(). Signed-off-by: Li Zefan --- kernel/cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3206137..4b92b9a 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2076,7 +2076,7 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) if (!group) return -ENOMEM; /* pre-allocate to guarantee space while iterating in rcu read-side. */ - retval = flex_array_prealloc(group, 0, group_size - 1, GFP_KERNEL); + retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL); if (retval) goto out_free_group_list; -- 1.8.0.2