From patchwork Wed Feb 23 21:19:54 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Marek_Marczykowski-G=C3=B3recki?= X-Patchwork-Id: 12757500 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FD61C4167E for ; Wed, 23 Feb 2022 21:20:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242535AbiBWVVK (ORCPT ); Wed, 23 Feb 2022 16:21:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242572AbiBWVUo (ORCPT ); Wed, 23 Feb 2022 16:20:44 -0500 Received: from wnew4-smtp.messagingengine.com (wnew4-smtp.messagingengine.com [64.147.123.18]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A3164EA0A; Wed, 23 Feb 2022 13:20:15 -0800 (PST) Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailnew.west.internal (Postfix) with ESMTP id 19BF52B001F4; Wed, 23 Feb 2022 16:20:14 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute1.internal (MEProxy); Wed, 23 Feb 2022 16:20:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:date:date:from:from:in-reply-to:message-id :mime-version:reply-to:sender:subject:subject:to:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=FgfAeo xPVPg0MdvPEZQn4ZDYWo1iiSPBcOv7dVpbcZk=; b=bUT6caj46S8Y5uir73PdHp VeSZBsQs2ia89NwbEoWUE5jKz56+1HvcKMM/1Xsok9Wu9Uv2ZV/HQK+EAjwN8ID6 BB39M2IyVs4stGSP4TGQpviphhzW+pGgOP2t88/SvuoW5ewOw2GGN+6/tOs0HZfb lzKPzsz+mnAOLCLetL33TYLnAq+UIzmNVkdr7ZAcQlcvyt/khgC1pd6hjNtUXdev DHGk8AekGNQspcmrhH2iX1WAQbI25PhOYOr31Qn1dS+W8AsU9q9nORUgcT2zpOx2 09hOTMHJulMFQKWK3JGTPGJa60Mw2FrX3hwi81rLy1IwVFb3A47UkV0K9JUFvVSw == X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvvddrledtgddugeeiucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvufffkffogggtohfgsehtkeertdertdejnecuhfhrohhmpeforghrvghk ucforghrtgiihihkohifshhkihdqifpkrhgvtghkihcuoehmrghrmhgrrhgvkhesihhnvh hishhisghlvghthhhinhhgshhlrggsrdgtohhmqeenucggtffrrghtthgvrhhnpeegvdef hfdtgfekfeevteekhfeivdeuvdejffeugfegfeffvdeuffevgfeuleetheenucffohhmrg hinhepghhithhhuhgsrdgtohhmnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghm pehmrghilhhfrhhomhepmhgrrhhmrghrvghksehinhhvihhsihgslhgvthhhihhnghhslh grsgdrtghomh X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 23 Feb 2022 16:20:10 -0500 (EST) From: =?utf-8?q?Marek_Marczykowski-G=C3=B3recki?= To: linux-kernel@vger.kernel.org Cc: =?utf-8?q?Marek_Marczykowski-G=C3=B3recki?= , stable@vger.kernel.org, Boris Ostrovsky , Juergen Gross , Stefano Stabellini , "David S. Miller" , Jakub Kicinski , Antoine Tenart , xen-devel@lists.xenproject.org (moderated list:XEN HYPERVISOR INTERFACE), netdev@vger.kernel.org (open list:NETWORKING DRIVERS) Subject: [PATCH v2] xen/netfront: destroy queues before real_num_tx_queues is zeroed Date: Wed, 23 Feb 2022 22:19:54 +0100 Message-Id: <20220223211954.2506824-1-marmarek@invisiblethingslab.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Organization: Invisible Things Lab Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org xennet_destroy_queues() relies on info->netdev->real_num_tx_queues to delete queues. Since d7dac083414eb5bb99a6d2ed53dc2c1b405224e5 ("net-sysfs: update the queue counts in the unregistration path"), unregister_netdev() indirectly sets real_num_tx_queues to 0. Those two facts together means, that xennet_destroy_queues() called from xennet_remove() cannot do its job, because it's called after unregister_netdev(). This results in kfree-ing queues that are still linked in napi, which ultimately crashes: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 1 PID: 52 Comm: xenwatch Tainted: G W 5.16.10-1.32.fc32.qubes.x86_64+ #226 RIP: 0010:free_netdev+0xa3/0x1a0 Code: ff 48 89 df e8 2e e9 00 00 48 8b 43 50 48 8b 08 48 8d b8 a0 fe ff ff 48 8d a9 a0 fe ff ff 49 39 c4 75 26 eb 47 e8 ed c1 66 ff <48> 8b 85 60 01 00 00 48 8d 95 60 01 00 00 48 89 ef 48 2d 60 01 00 RSP: 0000:ffffc90000bcfd00 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff88800edad000 RCX: 0000000000000000 RDX: 0000000000000001 RSI: ffffc90000bcfc30 RDI: 00000000ffffffff RBP: fffffffffffffea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: ffff88800edad050 R13: ffff8880065f8f88 R14: 0000000000000000 R15: ffff8880066c6680 FS: 0000000000000000(0000) GS:ffff8880f3300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000e998c006 CR4: 00000000003706e0 Call Trace: xennet_remove+0x13d/0x300 [xen_netfront] xenbus_dev_remove+0x6d/0xf0 __device_release_driver+0x17a/0x240 device_release_driver+0x24/0x30 bus_remove_device+0xd8/0x140 device_del+0x18b/0x410 ? _raw_spin_unlock+0x16/0x30 ? klist_iter_exit+0x14/0x20 ? xenbus_dev_request_and_reply+0x80/0x80 device_unregister+0x13/0x60 xenbus_dev_changed+0x18e/0x1f0 xenwatch_thread+0xc0/0x1a0 ? do_wait_intr_irq+0xa0/0xa0 kthread+0x16b/0x190 ? set_kthread_struct+0x40/0x40 ret_from_fork+0x22/0x30 Fix this by calling xennet_destroy_queues() from xennet_uninit(), when real_num_tx_queues is still available. This ensures that queues are destroyed when real_num_tx_queues is set to 0, regardless of how unregister_netdev() was called. Originally reported at https://github.com/QubesOS/qubes-issues/issues/7257 Fixes: d7dac083414eb5bb9 ("net-sysfs: update the queue counts in the unregistration path") Cc: stable@vger.kernel.org Signed-off-by: Marek Marczykowski-Górecki --- Changes in v2: - use xennet_uninit, as suggested by Jakub Kicinski --- drivers/net/xen-netfront.c | 39 ++++++++++++++++++++++---------------- 1 file changed, 23 insertions(+), 16 deletions(-) diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index d514d96027a6..039ca902c5bf 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -842,6 +842,28 @@ static int xennet_close(struct net_device *dev) return 0; } +static void xennet_destroy_queues(struct netfront_info *info) +{ + unsigned int i; + + for (i = 0; i < info->netdev->real_num_tx_queues; i++) { + struct netfront_queue *queue = &info->queues[i]; + + if (netif_running(info->netdev)) + napi_disable(&queue->napi); + netif_napi_del(&queue->napi); + } + + kfree(info->queues); + info->queues = NULL; +} + +static void xennet_uninit(struct net_device *dev) +{ + struct netfront_info *np = netdev_priv(dev); + xennet_destroy_queues(np); +} + static void xennet_set_rx_rsp_cons(struct netfront_queue *queue, RING_IDX val) { unsigned long flags; @@ -1611,6 +1633,7 @@ static int xennet_xdp(struct net_device *dev, struct netdev_bpf *xdp) } static const struct net_device_ops xennet_netdev_ops = { + .ndo_uninit = xennet_uninit, .ndo_open = xennet_open, .ndo_stop = xennet_close, .ndo_start_xmit = xennet_start_xmit, @@ -2103,22 +2126,6 @@ static int write_queue_xenstore_keys(struct netfront_queue *queue, return err; } -static void xennet_destroy_queues(struct netfront_info *info) -{ - unsigned int i; - - for (i = 0; i < info->netdev->real_num_tx_queues; i++) { - struct netfront_queue *queue = &info->queues[i]; - - if (netif_running(info->netdev)) - napi_disable(&queue->napi); - netif_napi_del(&queue->napi); - } - - kfree(info->queues); - info->queues = NULL; -} - static int xennet_create_page_pool(struct netfront_queue *queue)