From patchwork Sun Feb 20 13:42:01 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: 12752719 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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 670F6C433F5 for ; Sun, 20 Feb 2022 13:50:12 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.275850.471850 (Exim 4.92) (envelope-from ) id 1nLmam-0006SY-Vd; Sun, 20 Feb 2022 13:49:36 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 275850.471850; Sun, 20 Feb 2022 13:49:36 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1nLmam-0006SR-SS; Sun, 20 Feb 2022 13:49:36 +0000 Received: by outflank-mailman (input) for mailman id 275850; Sun, 20 Feb 2022 13:49:35 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1nLmak-0006SL-RA for xen-devel@lists.xenproject.org; Sun, 20 Feb 2022 13:49:35 +0000 Received: from wnew3-smtp.messagingengine.com (wnew3-smtp.messagingengine.com [64.147.123.17]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id ecb18b16-9253-11ec-8eb8-a37418f5ba1a; Sun, 20 Feb 2022 14:49:31 +0100 (CET) Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailnew.west.internal (Postfix) with ESMTP id 63AE62B00158; Sun, 20 Feb 2022 08:49:27 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute1.internal (MEProxy); Sun, 20 Feb 2022 08:49:28 -0500 Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 20 Feb 2022 08:49:25 -0500 (EST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: ecb18b16-9253-11ec-8eb8-a37418f5ba1a 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=Hzfm38 gwPt5b09qOmLkmmfY2IIYl8DekKzBTC8y6E/4=; b=Mh2eOvmHHkVx++fz80uns8 7+Y+xWxOHRMVpsAEIc1iX9iGRssSrqTt4DEoPDkKx1zMSVEFmktobYjSc+Q1vqpE NB3k0jRzA8yiLumKKiNCTPhOv39knberB8iIy1iNXVam1m3xZ6RSDAXrqrZv8jX+ 22yZfgzepiyULlT8Tz9i7x1r8X55zgZl8EZFYADfPMtKl/mzHfYyUHRn9F32L8x5 AKBkMSn9RahYlDyjeZLmzBXrhHBv5seX3OlpAlQfvr+eIxQRsqqhKWY76ow10uQ1 6Mdrffpszfy/cfGdr0ALfw3W1veNut0gsBQH0iw9CHa0rkPUs2n6BxamINmtawbw == X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvvddrkeeggdehkecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpefhvffufffkofggtghogfesthekredtredtjeenucfhrhhomhepofgrrhgvkhcu ofgrrhgtiiihkhhofihskhhiqdfikphrvggtkhhiuceomhgrrhhmrghrvghksehinhhvih hsihgslhgvthhhihhnghhslhgrsgdrtghomheqnecuggftrfgrthhtvghrnhepgedvfefh tdfgkeefveetkefhiedvuedvjeffuefggeefffdvueffvefgueelteehnecuffhomhgrih hnpehgihhthhhusgdrtghomhenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhep mhgrihhlfhhrohhmpehmrghrmhgrrhgvkhesihhnvhhishhisghlvghthhhinhhgshhlrg gsrdgtohhm X-ME-Proxy: 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] xen/netfront: destroy queues before real_num_tx_queues is zeroed Date: Sun, 20 Feb 2022 14:42:01 +0100 Message-Id: <20220220134202.2187485-1-marmarek@invisiblethingslab.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Organization: Invisible Things Lab 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_close() too, 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 # 5.16+ Signed-off-by: Marek Marczykowski-Górecki Reviewed-by: Juergen Gross --- While this fixes the issue, I'm not sure if that is the correct thing to do. xennet_remove() calls xennet_destroy_queues() under rtnl_lock, which may be important here? Just moving xennet_destroy_queues() before unregister_netdev() in xennet_remove() did not helped - it crashed in another way (use-after-free in xennet_close()). Signed-off-by: Marek Marczykowski-Górecki --- drivers/net/xen-netfront.c | 33 +++++++++++++++++---------------- 1 file changed, 17 insertions(+), 16 deletions(-) diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index d514d96027a6..5b69a930581e 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -828,6 +828,22 @@ static netdev_tx_t xennet_start_xmit(struct sk_buff *skb, struct net_device *dev return NETDEV_TX_OK; } +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_close(struct net_device *dev) { struct netfront_info *np = netdev_priv(dev); @@ -839,6 +855,7 @@ static int xennet_close(struct net_device *dev) queue = &np->queues[i]; napi_disable(&queue->napi); } + xennet_destroy_queues(np); return 0; } @@ -2103,22 +2120,6 @@ 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)