On Sat, 16 Mar 2019 13:24:39 +0800
Zhiqiang Liu <liuzhiqian...@huawei.com> wrote:
> I have updated the commit message as suggested by Eric. Even though I have
> read
> Documentation/networking/netdev-FAQ.rst as you mentioned. I am now still a
> little
> confused about the subject-prefix of v3 (net or net-next).
It's "net": this is a (likely critical) fix.
> And David Miller saied the net-next tree is CLOSED.
Right, but this is not for net-next anymore, given what Eric found.
> Could you help me check whether the following v3 patch is ok?
>
>
> Subject: [PATCH net v3] vxlan: remove the redundant gro_cells_destroy()
> calling.
This one. And it's not just redundant, so maybe something like:
"[PATCH net v3] vxlan: Don't call gro_cells_destroy() before
device is unregistered"
> OR
> Subject: [PATCH net-next v3] vxlan: remove the redundant gro_cells_destroy()
> calling.
>
> Commit ad6c9986bcb62 ("vxlan: Fix GRO cells race condition between
> receive and link delete") fixed a race condition for the typical case a vxlan
> device is dismantled from the current netns. But if a netns is dismantled,
> vxlan_destroy_tunnels() is called to schedule a unregister_netdevice_queue()
> of all the vxlan tunnels that are related to this netns.
>
> In vxlan_destroy_tunnels(), gro_cells_destroy() is called and finished before
> unregister_netdevice_queue(). This means that the gro_cells_destroy() call is
> done too soon, for the same reasons explained in above commit.
>
> So we need to fully respect the RCU rules, and thus must remove the
> gro_cells_destroy() call or risk use after-free.
>
> Fixes: 58ce31cca1ff ("vxlan: GRO support at tunnel layer")
> Signed-off-by: Suanming.Mou <mousuanm...@huawei.com>
> Suggested-by: Eric Dumazet <eric.duma...@gmail.com>
> Reviewed-by: Stefano Brivio <sbri...@redhat.com>
> Reviewed-by: Zhiqiang Liu <liuzhiqian...@huawei.com>
> ---
> V1->V2:
This will actually be v3.
> - update the commit message suggeted by Eric Dumazet
> - update Fixes: tag
>
> drivers/net/vxlan.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
> index 077f1b9f2761..d76dfed8d9bb 100644
> --- a/drivers/net/vxlan.c
> +++ b/drivers/net/vxlan.c
> @@ -4335,10 +4335,8 @@ static void vxlan_destroy_tunnels(struct net *net,
> struct list_head *head)
> /* If vxlan->dev is in the same netns, it has already been added
> * to the list by the previous loop.
> */
> - if (!net_eq(dev_net(vxlan->dev), net)) {
> - gro_cells_destroy(&vxlan->gro_cells);
> + if (!net_eq(dev_net(vxlan->dev), net))
> unregister_netdevice_queue(vxlan->dev, head);
> - }
> }
>
> for (h = 0; h < PORT_HASH_SIZE; ++h)
Looks good to me, you can keep my Reviewed-by: tag for v3. Thanks!
--
Stefano
