From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next] hv_netvsc: fix a race between netvsc_send() and netvsc_init_buf() Date: Fri, 21 Oct 2016 11:28:01 -0400 (EDT) Message-ID: <20161021.112801.585243295635293094.davem@davemloft.net> References: <1476885181-3456-1-git-send-email-vkuznets@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: sthemmin@microsoft.com, netdev@vger.kernel.org, haiyangz@microsoft.com, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org To: vkuznets@redhat.com Return-path: In-Reply-To: <1476885181-3456-1-git-send-email-vkuznets@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" List-Id: netdev.vger.kernel.org From: Vitaly Kuznetsov Date: Wed, 19 Oct 2016 15:53:01 +0200 > Fix in commit 880988348270 ("hv_netvsc: set nvdev link after populating > chn_table") turns out to be incomplete. A crash in > netvsc_get_next_send_section() is observed on mtu change when the device > is under load. The race I identified is: if we get to netvsc_send() after > we set net_device_ctx->nvdev link in netvsc_device_add() but before we > finish netvsc_connect_vsp()->netvsc_init_buf() send_section_map is not > allocated and we crash. Unfortunately we can't set net_device_ctx->nvdev > link after the netvsc_init_buf() call as during the negotiation we need > to receive packets and on the receive path we check for it. It would > probably be possible to split nvdev into a pair of nvdev_in and nvdev_out > links and check them accordingly in get_outbound_net_device()/ > get_inbound_net_device() but this looks like an overkill. > > Check that send_section_map is allocated in netvsc_send(). > > Signed-off-by: Vitaly Kuznetsov Applied, thanks.