From: Li Zefan Date: Tue, 12 Mar 2013 22:36:00 +0000 (-0700) Subject: cgroup: fix an off-by-one bug which may trigger BUG_ON() X-Git-Tag: v3.2.45~110 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=f596ca6c42fc4a8bb8269684ad2b839d78f684eb;p=thirdparty%2Fkernel%2Fstable.git cgroup: fix an off-by-one bug which may trigger BUG_ON() commit 3ac1707a13a3da9cfc8f242a15b2fae6df2c5f88 upstream. 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 Signed-off-by: Tejun Heo Signed-off-by: Ben Hutchings --- diff --git a/kernel/cgroup.c b/kernel/cgroup.c index c0739f88438a1..d2a01fee0d42c 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2029,7 +2029,7 @@ 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;