Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2993723AbbEPI3K (ORCPT ); Sat, 16 May 2015 04:29:10 -0400 Received: from bband-dyn183.178-41-215.t-com.sk ([178.41.215.183]:22846 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1030241AbbEPIRF (ORCPT ); Sat, 16 May 2015 04:17:05 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sabrina Dubroca , Jeff Kirsher , Jiri Slaby Subject: [PATCH 3.12 074/142] e1000: add dummy allocator to fix race condition between mtu change and netpoll Date: Sat, 16 May 2015 09:37:14 +0200 Message-Id: <47cd2dc5042d17bfa81e6d6ca52c6e019af0a871.1431761807.git.jslaby@suse.cz> X-Mailer: git-send-email 2.3.7 In-Reply-To: <70c3d4ae1322b9e9bd7443ef574af5635234a0fa.1431761807.git.jslaby@suse.cz> References: <70c3d4ae1322b9e9bd7443ef574af5635234a0fa.1431761807.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4037 Lines: 101 From: Sabrina Dubroca 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 08e8331654d1d7b2c58045e549005bc356aa7810 upstream. There is a race condition between e1000_change_mtu's cleanups and netpoll, when we change the MTU across jumbo size: Changing MTU frees all the rx buffers: e1000_change_mtu -> e1000_down -> e1000_clean_all_rx_rings -> e1000_clean_rx_ring Then, close to the end of e1000_change_mtu: pr_info -> ... -> netpoll_poll_dev -> e1000_clean -> e1000_clean_rx_irq -> e1000_alloc_rx_buffers -> e1000_alloc_frag And when we come back to do the rest of the MTU change: e1000_up -> e1000_configure -> e1000_configure_rx -> e1000_alloc_jumbo_rx_buffers alloc_jumbo finds the buffers already != NULL, since data (shared with page in e1000_rx_buffer->rxbuf) has been re-alloc'd, but it's garbage, or at least not what is expected when in jumbo state. This results in an unusable adapter (packets don't get through), and a NULL pointer dereference on the next call to e1000_clean_rx_ring (other mtu change, link down, shutdown): BUG: unable to handle kernel NULL pointer dereference at (null) IP: [] put_compound_page+0x7e/0x330 [...] Call Trace: [] put_page+0x55/0x60 [] e1000_clean_rx_ring+0x134/0x200 [] e1000_clean_all_rx_rings+0x45/0x60 [] e1000_down+0x1c0/0x1d0 [] ? deactivate_slab+0x7f0/0x840 [] e1000_change_mtu+0xdc/0x170 [] dev_set_mtu+0xa0/0x140 [] do_setlink+0x218/0xac0 [] ? nla_parse+0xb9/0x120 [] rtnl_newlink+0x6d0/0x890 [] ? kvm_clock_read+0x20/0x40 [] ? sched_clock_cpu+0xa8/0x100 [] rtnetlink_rcv_msg+0x92/0x260 By setting the allocator to a dummy version, netpoll can't mess up our rx buffers. The allocator is set back to a sane value in e1000_configure_rx. Fixes: edbbb3ca1077 ("e1000: implement jumbo receive with partial descriptors") Signed-off-by: Sabrina Dubroca Tested-by: Aaron Brown Signed-off-by: Jeff Kirsher Signed-off-by: Jiri Slaby --- drivers/net/ethernet/intel/e1000/e1000_main.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c index 15c85d4f3774..b7f68883da64 100644 --- a/drivers/net/ethernet/intel/e1000/e1000_main.c +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c @@ -144,6 +144,11 @@ static bool e1000_clean_rx_irq(struct e1000_adapter *adapter, static bool e1000_clean_jumbo_rx_irq(struct e1000_adapter *adapter, struct e1000_rx_ring *rx_ring, int *work_done, int work_to_do); +static void e1000_alloc_dummy_rx_buffers(struct e1000_adapter *adapter, + struct e1000_rx_ring *rx_ring, + int cleaned_count) +{ +} static void e1000_alloc_rx_buffers(struct e1000_adapter *adapter, struct e1000_rx_ring *rx_ring, int cleaned_count); @@ -3566,8 +3571,11 @@ static int e1000_change_mtu(struct net_device *netdev, int new_mtu) msleep(1); /* e1000_down has a dependency on max_frame_size */ hw->max_frame_size = max_frame; - if (netif_running(netdev)) + if (netif_running(netdev)) { + /* prevent buffers from being reallocated */ + adapter->alloc_rx_buf = e1000_alloc_dummy_rx_buffers; e1000_down(adapter); + } /* NOTE: netdev_alloc_skb reserves 16 bytes, and typically NET_IP_ALIGN * means we reserve 2 more, this pushes us to allocate from the next -- 2.3.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/