On 06/05/2017 12:58 PM, Levin, Alexander (Sasha Levin) wrote:
> On Mon, Jun 05, 2017 at 09:56:18AM -0700, Florian Fainelli wrote:
>> On 06/05/2017 05:15 AM, Levin, Alexander (Sasha Levin) wrote:
>>> On Sun, Jun 04, 2017 at 10:17:49AM -0700, Florian Fainelli wrote:
>>>> Hi Alex,
>>>>
>>>> On 06/04/2017 01:12 AM, Levin, Alexander (Sasha Levin) wrote:
>>>>> From: Mao Wenan <maowenan@xxxxxxxxxx>
>>>>>
>>>>> [ 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 <maowenan@xxxxxxxxxx>
>>>>> [florian: rebase, rework commit message]
>>>>> Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
>>>>> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
>>>>>
>>>>> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
>>>>
>>>> This commit alone will cause problems, you will also need to pick this
>>>> one on top of it:
>>>>
>>>> 6d9f66ac7fec2a6ccd649e5909806dfe36f1fc25 ("net: phy: Fix PHY module
>>>> checks and NULL deref in phy_attach_direct()")
>>>
>>> Should I also be grabbing a7dac9f9c1
>>> ("phy: fix error case of phy_led_triggers_(un)register")?
>>>
>>> It says it fixes a commit that's not in -stable, but it looks like it's
>>> still relevant even without that commit.
>>
>> No, you don't have to pick this one, it does indeed fix something that
>> was only introduced in 4.10 and newer.
>
> Hm, can you ack this conflict resolution of applying 6d9f66ac7fe on top
> of 4.9.30 (in particular, the code in phy_attach_direct()):
The resolution looks good at first glance, but I will run this through
the tests that required the cooking of these patches in the first place.
Will respond in a few hours, thanks!
>
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 686bca0ba820..a8082d3d70e3 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -860,6 +860,7 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
> struct module *ndev_owner = dev->dev.parent->driver->owner;
> struct mii_bus *bus = phydev->mdio.bus;
> struct device *d = &phydev->mdio.dev;
> + bool using_genphy = false;
> int err;
>
> /* For Ethernet device drivers that register their own MDIO bus, we
> @@ -872,11 +873,6 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
> 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
> @@ -890,12 +886,22 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
> d->driver =
> &genphy_driver[GENPHY_DRV_1G].mdiodrv.driver;
>
> + using_genphy = true;
> + }
> +
> + if (!try_module_get(d->driver->owner)) {
> + dev_err(&dev->dev, "failed to get the device driver module\n");
> + err = -EIO;
> + goto error_put_device;
> + }
> +
> + if (using_genphy) {
> err = d->driver->probe(d);
> if (err >= 0)
> err = device_bind_driver(d);
>
> if (err)
> - goto error;
> + goto error_module_put;
> }
>
> if (phydev->attached_dev) {
> @@ -931,8 +937,12 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
> return err;
>
> error:
> - put_device(d);
> + return err;
> +
> +error_module_put:
> module_put(d->driver->owner);
> +error_put_device:
> + put_device(d);
> if (ndev_owner != bus->owner)
> module_put(bus->owner);
> return err;
> @@ -993,6 +1003,8 @@ void phy_detach(struct phy_device *phydev)
> phydev->attached_dev = NULL;
> phy_suspend(phydev);
>
> + module_put(phydev->mdio.dev.driver->owner);
> +
> /* If the device had no specific driver before (i.e. - it
> * was using the generic driver), we unbind the device
> * from the generic driver so that there's a chance a
> @@ -1013,7 +1025,6 @@ void phy_detach(struct phy_device *phydev)
> 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);
> }
>
> --
>
> Thanks,
> Sasha
>
--
Florian