From mboxrd@z Thu Jan 1 00:00:00 1970 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 0F8FAC433EF for ; Sat, 5 Mar 2022 13:54:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229526AbiCENzA (ORCPT ); Sat, 5 Mar 2022 08:55:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52576 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229448AbiCENy7 (ORCPT ); Sat, 5 Mar 2022 08:54:59 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C04BD1CABC5 for ; Sat, 5 Mar 2022 05:54:09 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5970D612BB for ; Sat, 5 Mar 2022 13:54:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 454AAC004E1; Sat, 5 Mar 2022 13:54:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646488448; bh=/I5JlV1PMbp5hlvxRrEszK0/5nfsedfo0enrFBJk0nw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=o49IPgTXsAdI6no4fITCEZMD/IjHno8JefZhbKg4J9o/Wd1zpymNTPeOtMxKW5plB QGf/3+OVCxaf/eKQUflv0Uc+cXhLUqzON1RZcPiaDcPUS/sw8hhriGVI5mkeksV7wQ 9lWmDs6ee9hLjY+VL4JSptqslfBiyTp6Fl70s17k= Date: Sat, 5 Mar 2022 14:54:04 +0100 From: Greg KH To: Marek =?iso-8859-1?Q?Marczykowski-G=F3recki?= Cc: stable@vger.kernel.org, "David S . Miller" Subject: Re: [PATCH 5.4,4.19] xen/netfront: destroy queues before real_num_tx_queues is zeroed Message-ID: References: <20220305132616.3464066-1-marmarek@invisiblethingslab.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220305132616.3464066-1-marmarek@invisiblethingslab.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Sat, Mar 05, 2022 at 02:26:17PM +0100, Marek Marczykowski-Górecki wrote: > commit dcf4ff7a48e7598e6b10126cc02177abb8ae4f3f upstream. > > 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 > Signed-off-by: David S. Miller > --- > drivers/net/xen-netfront.c | 39 ++++++++++++++++++++++---------------- > 1 file changed, 23 insertions(+), 16 deletions(-) Now queued up, thanks. greg k-h