4.9-stable review patch. If anyone has any objections, please let me know.
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From: Zhiqiang Liu liuzhiqiang26@huawei.com
[ Upstream commit cc4807bb609230d8959fd732b0bf3bd4c2de8eac ]
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 mousuanming@huawei.com Suggested-by: Eric Dumazet eric.dumazet@gmail.com Reviewed-by: Stefano Brivio sbrivio@redhat.com Reviewed-by: Zhiqiang Liu liuzhiqiang26@huawei.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/vxlan.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
--- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -3375,10 +3375,8 @@ static void __net_exit vxlan_exit_net(st /* 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, &list); - } }
unregister_netdevice_many(&list);