On Mon, Apr 07, 2014 at 04:51:58PM +0200, Pablo Neira Ayuso wrote:

On Mon, Mar 31, 2014 at 06:14:18PM +0400, Andrey Vagin wrote:

quoted

nf_ct_gre_keymap_flush() removes a nf_ct_gre_keymap object from
net_gre->keymap_list and frees the object. But it doesn't clean
a reference on this object from ct_pptp_info->keymap[dir].
Then nf_ct_gre_keymap_destroy() may release the same object again.

So nf_ct_gre_keymap_flush() can be called only when we are sure that
when nf_ct_gre_keymap_destroy will not be called.

nf_ct_gre_keymap is created by nf_ct_gre_keymap_add() and the right way
to destroy it is to call nf_ct_gre_keymap_destroy().

I think you use call nf_ct_iterate_cleanup() to get rid of all GRE
conntrack entries that have a ct->master, which means that they were
created by PPTP. That implicitly calls gre_destroy, which releases the
keymap object.

I'm not sure that I understand your comment. Currently I change nothing
about nf_ct_iterate_cleanup(). In this sentence I point to the right
procedure of destroying a gre conntrack.

nf_ct_iterate_cleanup() is called from nf_ct_l4proto_pernet_unregister().

[ 1858.693250]   <idle>-0       1..s. 118795582us : nf_ct_gre_keymap_add <-exp_gre
[ 1858.693250]   <idle>-0       1..s. 118795598us : nf_ct_gre_keymap_add <-exp_gre
[ 1858.693250]   <idle>-0       1..s. 118795652us : nf_ct_gre_keymap_add <-exp_gre
[ 1858.693250]   <idle>-0       1..s. 118795683us : nf_ct_gre_keymap_add <-exp_gre
[ 1858.693250] kworker/-44      1.... 133620272us : nf_conntrack_pptp_net_exit <-ops_exit_list.isra.1
[ 1858.693250] kworker/-44      1.... 133620274us : nf_ct_gre_keymap_flush <-nf_conntrack_pptp_net_exit
[ 1858.693250] kworker/-44      1.... 133621145us : proto_gre_net_exit <-ops_exit_list.isra.1
[ 1858.693250] kworker/-44      1.... 133621145us : nf_ct_l4proto_pernet_unregister <-proto_gre_net_exit
[ 1858.693250] kworker/-44      1.... 133621146us : nf_ct_iterate_cleanup <-nf_ct_l4proto_pernet_unregister
[ 1858.693250] kworker/-44      1.... 133621187us : nf_ct_gre_keymap_destroy <-gre_destroy

quoted

This patch marks nf_ct_gre_keymap_flush() as static, so this patch can
break compilation of third party modules, which use
nf_ct_gre_keymap_flush. I'm not sure this is the right way to deprecate
this function.

No problem with that, we don't mind about out of tree modules. With
the approach I'm proposing I think you will also need to make this
function static as it won't be used by PPTP anymore.

I have made this function static. If you don't have other comment, could
you take this patch?

Thanks,
Andrey