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cgroup: fix an off-by-one bug which may trigger BUG_ON() 

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 <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
This commit is contained in:
Li Zefan 2013-03-12 15:36:00 -07:00 committed by Tejun Heo
parent 80f36c2a1a
commit 3ac1707a13
1 changed files with 1 additions and 1 deletions
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2
kernel/cgroup.c
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@ -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;