Messages in this thread | | | Date | Tue, 18 Feb 2014 18:20:56 -0500 | From | Tejun Heo <> | Subject | Re: [PATCH] cgroup: add a validation check to cgroup_add_cftyps() |
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On Mon, Feb 17, 2014 at 10:41:50AM +0800, Li Zefan wrote: > Fengguang reported this bug: > > BUG: unable to handle kernel NULL pointer dereference at 0000003c > IP: [<cc90b4ad>] cgroup_cfts_commit+0x27/0x1c1 > ... > Call Trace: > [<cc9d1129>] ? kmem_cache_alloc_trace+0x33f/0x3b7 > [<cc90c6fc>] cgroup_add_cftypes+0x8f/0xca > [<cd78b646>] cgroup_init+0x6a/0x26a > [<cd764d7d>] start_kernel+0x4d7/0x57a > [<cd7642ef>] i386_start_kernel+0x92/0x96 > > This happens in a corner case. If CGROUP_SCHED=y but CFS_BANDWIDTH=n && > FAIR_GROUP_SCHED=n && RT_GROUP_SCHED=n, we have: > > cpu_files[] = { > { } /* terminate */ > } > > When we pass cpu_files to cgroup_apply_cftypes(), as cpu_files[0].ss > is NULL, we'll access NULL pointer. > > The bug was introduced by commit de00ffa56ea3132c6013fc8f07133b8a1014cf53 > ("cgroup: make cgroup_subsys->base_cftypes use cgroup_add_cftypes()"). > > Reported-by: Fengguang Wu <fengguang.wu@intel.com> > Signed-off-by: Li Zefan <lizefan@huawei.com>
Applied to cgroup/for-3.15. Thanks.
-- tejun
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