Messages in this thread | | | Subject | Re: [PATCH] cgroup: fix panic in netprio_cgroup | From | Eric Dumazet <> | Date | Thu, 05 Jul 2012 10:43:29 +0200 |
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On Thu, 2012-07-05 at 16:31 +0800, Gao feng wrote: > we set max_prioidx to the first zero bit index of prioidx_map in > function get_prioidx. > > So when we delete the low index netprio cgroup and adding a new > netprio cgroup again,the max_prioidx will be set to the low index. > > when we set the high index cgroup's net_prio.ifpriomap,the function > write_priomap will call update_netdev_tables to alloc memory which > size is sizeof(struct netprio_map) + sizeof(u32) * (max_prioidx + 1), > so the size of array that map->priomap point to is max_prioidx +1, > which is low than what we actually need. > > fix this by adding check in get_prioidx,only set max_prioidx when > max_prioidx low than the new prioidx. > > Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com> > --- > net/core/netprio_cgroup.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c > index 5b8aa2f..586f7d9 100644 > --- a/net/core/netprio_cgroup.c > +++ b/net/core/netprio_cgroup.c > @@ -50,7 +50,8 @@ static int get_prioidx(u32 *prio) > } > set_bit(prioidx, prioidx_map); > spin_unlock_irqrestore(&prioidx_map_lock, flags); > - atomic_set(&max_prioidx, prioidx); > + if (atomic_read(&max_prioidx) < prioidx) > + atomic_set(&max_prioidx, prioidx); > *prio = prioidx; > return 0; > }
This is still racy.
Please do this before the spin_unlock_irqrestore(&prioidx_map_lock, flags);
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