From 152669bd3cd2407d6f556009b95ee249c0c1a462 Mon Sep 17 00:00:00 2001 From: Dexuan Cui Date: Thu, 2 Mar 2017 13:00:53 +0000 Subject: [PATCH] netvsc: fix use-after-free in netvsc_change_mtu() 'nvdev' is freed in rndis_filter_device_remove -> netvsc_device_remove -> free_netvsc_device, so we mustn't access it, before it's re-created in rndis_filter_device_add -> netvsc_device_add. Signed-off-by: Dexuan Cui Cc: "K. Y. Srinivasan" Cc: Haiyang Zhang Cc: Stephen Hemminger Reviewed-by: Stephen Hemminger Signed-off-by: David S. Miller --- drivers/net/hyperv/netvsc_drv.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 2d3cdb026a99..bc05c895d958 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -859,15 +859,22 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu) if (ret) goto out; - ndevctx->start_remove = true; - rndis_filter_device_remove(hdev, nvdev); - - ndev->mtu = mtu; - memset(&device_info, 0, sizeof(device_info)); device_info.ring_size = ring_size; device_info.num_chn = nvdev->num_chn; device_info.max_num_vrss_chns = nvdev->num_chn; + + ndevctx->start_remove = true; + rndis_filter_device_remove(hdev, nvdev); + + /* 'nvdev' has been freed in rndis_filter_device_remove() -> + * netvsc_device_remove () -> free_netvsc_device(). + * We mustn't access it before it's re-created in + * rndis_filter_device_add() -> netvsc_device_add(). + */ + + ndev->mtu = mtu; + rndis_filter_device_add(hdev, &device_info); out: