Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753282AbdFOR56 (ORCPT ); Thu, 15 Jun 2017 13:57:58 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:54388 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751141AbdFOR5y (ORCPT ); Thu, 15 Jun 2017 13:57:54 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mao Wenan , Florian Fainelli , "David S. Miller" , Sasha Levin Subject: [PATCH 4.9 036/108] net: phy: Fix lack of reference count on PHY driver Date: Thu, 15 Jun 2017 19:52:42 +0200 Message-Id: <20170615175338.885969134@linuxfoundation.org> X-Mailer: git-send-email 2.13.1 In-Reply-To: <20170615175337.190782107@linuxfoundation.org> References: <20170615175337.190782107@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3717 Lines: 101 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mao Wenan [ Upstream commit cafe8df8b9bc9aa3dffa827c1a6757c6cd36f657 ] There is currently no reference count being held on the PHY driver, which makes it possible to remove the PHY driver module while the PHY state machine is running and polling the PHY. This could cause crashes similar to this one to show up: [ 43.361162] BUG: unable to handle kernel NULL pointer dereference at 0000000000000140 [ 43.361162] IP: phy_state_machine+0x32/0x490 [ 43.361162] PGD 59dc067 [ 43.361162] PUD 0 [ 43.361162] [ 43.361162] Oops: 0000 [#1] SMP [ 43.361162] Modules linked in: dsa_loop [last unloaded: broadcom] [ 43.361162] CPU: 0 PID: 1299 Comm: kworker/0:3 Not tainted 4.10.0-rc5+ #415 [ 43.361162] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu2 04/01/2014 [ 43.361162] Workqueue: events_power_efficient phy_state_machine [ 43.361162] task: ffff880006782b80 task.stack: ffffc90000184000 [ 43.361162] RIP: 0010:phy_state_machine+0x32/0x490 [ 43.361162] RSP: 0018:ffffc90000187e18 EFLAGS: 00000246 [ 43.361162] RAX: 0000000000000000 RBX: ffff8800059e53c0 RCX: ffff880006a15c60 [ 43.361162] RDX: ffff880006782b80 RSI: 0000000000000000 RDI: ffff8800059e5428 [ 43.361162] RBP: ffffc90000187e48 R08: ffff880006a15c40 R09: 0000000000000000 [ 43.361162] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8800059e5428 [ 43.361162] R13: ffff8800059e5000 R14: 0000000000000000 R15: ffff880006a15c40 [ 43.361162] FS: 0000000000000000(0000) GS:ffff880006a00000(0000) knlGS:0000000000000000 [ 43.361162] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 43.361162] CR2: 0000000000000140 CR3: 0000000005979000 CR4: 00000000000006f0 [ 43.361162] Call Trace: [ 43.361162] process_one_work+0x1b4/0x3e0 [ 43.361162] worker_thread+0x43/0x4d0 [ 43.361162] ? __schedule+0x17f/0x4e0 [ 43.361162] kthread+0xf7/0x130 [ 43.361162] ? process_one_work+0x3e0/0x3e0 [ 43.361162] ? kthread_create_on_node+0x40/0x40 [ 43.361162] ret_from_fork+0x29/0x40 [ 43.361162] Code: 56 41 55 41 54 4c 8d 67 68 53 4c 8d af 40 fc ff ff 48 89 fb 4c 89 e7 48 83 ec 08 e8 c9 9d 27 00 48 8b 83 60 ff ff ff 44 8b 73 98 <48> 8b 90 40 01 00 00 44 89 f0 48 85 d2 74 08 4c 89 ef ff d2 8b Keep references on the PHY driver module right before we are going to utilize it in phy_attach_direct(), and conversely when we don't use it anymore in phy_detach(). Signed-off-by: Mao Wenan [florian: rebase, rework commit message] Signed-off-by: Florian Fainelli Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/net/phy/phy_device.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -872,6 +872,11 @@ int phy_attach_direct(struct net_device return -EIO; } + if (!try_module_get(d->driver->owner)) { + dev_err(&dev->dev, "failed to get the device driver module\n"); + return -EIO; + } + get_device(d); /* Assume that if there is no driver, that it doesn't @@ -927,6 +932,7 @@ int phy_attach_direct(struct net_device error: put_device(d); + module_put(d->driver->owner); if (ndev_owner != bus->owner) module_put(bus->owner); return err; @@ -1007,6 +1013,7 @@ void phy_detach(struct phy_device *phyde bus = phydev->mdio.bus; put_device(&phydev->mdio.dev); + module_put(phydev->mdio.dev.driver->owner); if (ndev_owner != bus->owner) module_put(bus->owner); }