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()")
Thanks!
> ---
> drivers/net/phy/phy_device.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index c4ceb082e970..67571f9627e5 100644
> --- 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 *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
> @@ -927,6 +932,7 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
>
> 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 *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);
> }
>
--
Florian