Re: [PATCH v3] net: cgroup: fix access the unallocated memory in netprio cgroup

[Gao feng <gaofeng@cn.fujitsu.com>]

于 2012年07月11日 20:11, Neil Horman 写道:
> On Wed, Jul 11, 2012 at 04:30:06PM +0800, Gao feng wrote:
>> there are some out of bound accesses in netprio cgroup.
>>
>> now before accessing the dev->priomap.priomap array,we only check
>> if the dev->priomap exist.and because we don't want to see
>> additional bound checkings in fast path, so we should make sure
>> that dev->priomap is null or array size of dev->priomap.priomap
>> is equal to max_prioidx + 1;
>>
>> and it's not needed to call extend_netdev_tabel in write_priomap,
>> we can only allocate the net device's priomap which we change through
>> net_prio.ifpriomap.
>>
>> this patch add a return value for update_netdev_tables & extend_netdev_table,
>> so when new_priomap is allocated failed,write_priomap will stop to access
>> the priomap,and return -ENOMEM back to the userspace to tell the user
>> what happend.
>>
>> Change From v2:
>> 1. protect extend_netdev_table by RTNL.
>> 2. when extend_netdev_table failed,call dev_put to reduce device's refcount.
>>
>> Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
>> Cc: Neil Horman <nhorman@tuxdriver.com>
>> Cc: Eric Dumazet <edumazet@google.com>
>> ---
>>  net/core/netprio_cgroup.c |   54 ++++++++++++++++++++++++++++++++------------
>>  1 files changed, 39 insertions(+), 15 deletions(-)
>>
> I still think the use of max_priomap in write_priomap is racy (please see my
> previous note).
> 
> Neil

Yes, you are right :(
we need a v4 patch.

Thanks!