[PATCH 7/8] cgroup: fix an almost harmless off-by-one bug

[Li Zefan]

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@xxxxxxxxxx>
---
 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

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