From: Menglong Dong <[email protected]>
This commit seems make no sense, as bridge is destroyed when
br_multicast_dev_del is called.
In commit b1b9d366028f
("bridge: move bridge multicast cleanup to ndo_uninit"), Xin Long
fixed the use-after-free panic in br_multicast_group_expired by
moving br_multicast_dev_del to ndo_uninit. However, that patch is
not applied to 4.4.X, and the bug exists.
Fix that bug by disabling multicast in br_multicast_dev_del for
4.4.X, and there is no harm for other branches.
Signed-off-by: Menglong Dong <[email protected]>
---
net/bridge/br_multicast.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index eae898c3cff7..9992fdff2951 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -3369,6 +3369,7 @@ void br_multicast_dev_del(struct net_bridge *br)
hlist_for_each_entry_safe(mp, tmp, &br->mdb_list, mdb_node)
br_multicast_del_mdb_entry(mp);
hlist_move_list(&br->mcast_gc_list, &deleted_head);
+ br_opt_toggle(br, BROPT_MULTICAST_ENABLED, false);
spin_unlock_bh(&br->multicast_lock);
br_multicast_gc(&deleted_head);
--
2.25.1
On Mon, 2020-11-02 at 22:38 +0800, Menglong Dong wrote:
> From: Menglong Dong <[email protected]>
>
> This commit seems make no sense, as bridge is destroyed when
> br_multicast_dev_del is called.
>
> In commit b1b9d366028f
> ("bridge: move bridge multicast cleanup to ndo_uninit"), Xin Long
> fixed the use-after-free panic in br_multicast_group_expired by
> moving br_multicast_dev_del to ndo_uninit. However, that patch is
> not applied to 4.4.X, and the bug exists.
>
> Fix that bug by disabling multicast in br_multicast_dev_del for
> 4.4.X, and there is no harm for other branches.
>
> Signed-off-by: Menglong Dong <[email protected]>
> ---
> net/bridge/br_multicast.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
> index eae898c3cff7..9992fdff2951 100644
> --- a/net/bridge/br_multicast.c
> +++ b/net/bridge/br_multicast.c
> @@ -3369,6 +3369,7 @@ void br_multicast_dev_del(struct net_bridge *br)
> hlist_for_each_entry_safe(mp, tmp, &br->mdb_list, mdb_node)
> br_multicast_del_mdb_entry(mp);
> hlist_move_list(&br->mcast_gc_list, &deleted_head);
> + br_opt_toggle(br, BROPT_MULTICAST_ENABLED, false);
> spin_unlock_bh(&br->multicast_lock);
>
> br_multicast_gc(&deleted_head);
This doesn't make any sense. It doesn't fix anything.
If 4.4 has a problem then the relevant patches should get backported to it.
We don't add random changes to fix older releases.
Cheers,
Nik
Nacked-by: Nikolay Aleksandrov <[email protected]>
Dear Nik,
On Wed, Nov 4, 2020 at 12:26 AM Nikolay Aleksandrov <[email protected]> wrote:
>
> On Mon, 2020-11-02 at 22:38 +0800, Menglong Dong wrote:
> > From: Menglong Dong <[email protected]>
> >
> > This commit seems make no sense, as bridge is destroyed when
> > br_multicast_dev_del is called.
> >
> > In commit b1b9d366028f
> > ("bridge: move bridge multicast cleanup to ndo_uninit"), Xin Long
> > fixed the use-after-free panic in br_multicast_group_expired by
> > moving br_multicast_dev_del to ndo_uninit. However, that patch is
> > not applied to 4.4.X, and the bug exists.
> >
> > Fix that bug by disabling multicast in br_multicast_dev_del for
> > 4.4.X, and there is no harm for other branches.
> >
> > Signed-off-by: Menglong Dong <[email protected]>
> > ---
> > net/bridge/br_multicast.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
> > index eae898c3cff7..9992fdff2951 100644
> > --- a/net/bridge/br_multicast.c
> > +++ b/net/bridge/br_multicast.c
> > @@ -3369,6 +3369,7 @@ void br_multicast_dev_del(struct net_bridge *br)
> > hlist_for_each_entry_safe(mp, tmp, &br->mdb_list, mdb_node)
> > br_multicast_del_mdb_entry(mp);
> > hlist_move_list(&br->mcast_gc_list, &deleted_head);
> > + br_opt_toggle(br, BROPT_MULTICAST_ENABLED, false);
> > spin_unlock_bh(&br->multicast_lock);
> >
> > br_multicast_gc(&deleted_head);
>
> This doesn't make any sense. It doesn't fix anything.
> If 4.4 has a problem then the relevant patches should get backported to it.
> We don't add random changes to fix older releases.
>
> Cheers,
> Nik
>
> Nacked-by: Nikolay Aleksandrov <[email protected]>
Thanks for your patient explanation, and I see it now~
Cheers,
Menglong Dong