On Mon, Jun 05, 2017 at 05:33:08PM -0700, Florian Fainelli wrote:
> 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()):
>
> Acked-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
>
> Sorry it took a bit of time for testing because I also exercised the
> error paths to make sure it was not blowing up on us, FWIW, attached was
> the patch that I used.
> --
> Florian
I'll take your patch below. Thanks Florian!
> From 2a33694744e3ed2d33c4a530118ab46d20fbe6fc Mon Sep 17 00:00:00 2001
> From: Florian Fainelli <f.fainelli@xxxxxxxxx>
> Date: Wed, 8 Feb 2017 19:05:26 -0800
> Subject: [PATCH] net: phy: Fix PHY module checks and NULL deref in
> phy_attach_direct()
>
> The Generic PHY drivers gets assigned after we checked that the current
> PHY driver is NULL, so we need to check a few things before we can
> safely dereference d->driver. This would be causing a NULL deference to
> occur when a system binds to the Generic PHY driver. Update
> phy_attach_direct() to do the following:
>
> - grab the driver module reference after we have assigned the Generic
> PHY drivers accordingly, and remember we came from the generic PHY
> path
>
> - update the error path to clean up the module reference in case the
> Generic PHY probe function fails
>
> - split the error path involving phy_detacht() to avoid double free/put
> since phy_detach() does all the clean up
>
> - finally, have phy_detach() drop the module reference count before we
> call device_release_driver() for the Generic PHY driver case
>
> Fixes: cafe8df8b9bc ("net: phy: Fix lack of reference count on PHY driver")
> Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> ---
> drivers/net/phy/phy_device.c | 29 +++++++++++++++++++++--------
> 1 file changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 67571f9627e5..14d57d0d1c04 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 +937,14 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
> return err;
>
> error:
> - put_device(d);
> + /* phy_detach() does all of the cleanup below */
> + phy_detach(phydev);
> + 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 +1005,8 @@ 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 +1027,6 @@ 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);
> }
> --
> 2.9.3
>
--
Thanks,
Sasha