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 <[email protected]> Signed-off-by: Tejun Heo <[email protected]> Cc: [email protected]
gunnarahlberg · Mar 20, 2013 · 3ac1707 · 3ac1707
1 parent 80f36c2
commit 3ac1707
Showing 1 changed file with 1 addition and 1 deletion.
diff --git 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;