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    Subject[ 59/69] USB: serial: Enforce USB driver and USB serial driver match
    3.2-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Bjørn Mork <bjorn@mork.no>

    commit 954c3f8a5f1b7716be9eee978b3bc85bae92d7c8 upstream.

    We need to make sure that the USB serial driver we find
    matches the USB driver whose probe we are currently
    executing. Otherwise we will end up with USB serial
    devices bound to the correct serial driver but wrong
    USB driver.

    An example of such cross-probing, where the usbserial_generic
    USB driver has found the sierra serial driver:

    May 29 18:26:15 nemi kernel: [ 4442.559246] usbserial_generic 4-4:1.0: Sierra USB modem converter detected
    May 29 18:26:20 nemi kernel: [ 4447.556747] usbserial_generic 4-4:1.2: Sierra USB modem converter detected
    May 29 18:26:25 nemi kernel: [ 4452.557288] usbserial_generic 4-4:1.3: Sierra USB modem converter detected

    sysfs view of the same problem:

    bjorn@nemi:~$ ls -l /sys/bus/usb/drivers/sierra/
    total 0
    --w------- 1 root root 4096 May 29 18:23 bind
    lrwxrwxrwx 1 root root 0 May 29 18:23 module -> ../../../../module/usbserial
    --w------- 1 root root 4096 May 29 18:23 uevent
    --w------- 1 root root 4096 May 29 18:23 unbind
    bjorn@nemi:~$ ls -l /sys/bus/usb-serial/drivers/sierra/
    total 0
    --w------- 1 root root 4096 May 29 18:23 bind
    lrwxrwxrwx 1 root root 0 May 29 18:23 module -> ../../../../module/sierra
    -rw-r--r-- 1 root root 4096 May 29 18:23 new_id
    lrwxrwxrwx 1 root root 0 May 29 18:32 ttyUSB0 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.0/ttyUSB0
    lrwxrwxrwx 1 root root 0 May 29 18:32 ttyUSB1 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.2/ttyUSB1
    lrwxrwxrwx 1 root root 0 May 29 18:32 ttyUSB2 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.3/ttyUSB2
    --w------- 1 root root 4096 May 29 18:23 uevent
    --w------- 1 root root 4096 May 29 18:23 unbind

    bjorn@nemi:~$ ls -l /sys/bus/usb/drivers/usbserial_generic/
    total 0
    lrwxrwxrwx 1 root root 0 May 29 18:33 4-4:1.0 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.0
    lrwxrwxrwx 1 root root 0 May 29 18:33 4-4:1.2 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.2
    lrwxrwxrwx 1 root root 0 May 29 18:33 4-4:1.3 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.3
    --w------- 1 root root 4096 May 29 18:33 bind
    lrwxrwxrwx 1 root root 0 May 29 18:33 module -> ../../../../module/usbserial
    --w------- 1 root root 4096 May 29 18:22 uevent
    --w------- 1 root root 4096 May 29 18:33 unbind
    bjorn@nemi:~$ ls -l /sys/bus/usb-serial/drivers/generic/
    total 0
    --w------- 1 root root 4096 May 29 18:33 bind
    lrwxrwxrwx 1 root root 0 May 29 18:33 module -> ../../../../module/usbserial
    -rw-r--r-- 1 root root 4096 May 29 18:33 new_id
    --w------- 1 root root 4096 May 29 18:22 uevent
    --w------- 1 root root 4096 May 29 18:33 unbind

    So we end up with a mismatch between the USB driver and the
    USB serial driver. The reason for the above is simple: The
    USB driver probe will succeed if *any* registered serial
    driver matches, and will use that serial driver for all
    serial driver functions.

    This makes ref counting go wrong. We count the USB driver
    as used, but not the USB serial driver. This may result
    in Oops'es as demonstrated by Johan Hovold <jhovold@gmail.com>:

    [11811.646396] drivers/usb/serial/usb-serial.c: get_free_serial 1
    [11811.646443] drivers/usb/serial/usb-serial.c: get_free_serial - minor base = 0
    [11811.646460] drivers/usb/serial/usb-serial.c: usb_serial_probe - registering ttyUSB0
    [11811.646766] usb 6-1: pl2303 converter now attached to ttyUSB0
    [11812.264197] USB Serial deregistering driver FTDI USB Serial Device
    [11812.264865] usbcore: deregistering interface driver ftdi_sio
    [11812.282180] USB Serial deregistering driver pl2303
    [11812.283141] pl2303 ttyUSB0: pl2303 converter now disconnected from ttyUSB0
    [11812.283272] usbcore: deregistering interface driver pl2303
    [11812.301056] USB Serial deregistering driver generic
    [11812.301186] usbcore: deregistering interface driver usbserial_generic
    [11812.301259] drivers/usb/serial/usb-serial.c: usb_serial_disconnect
    [11812.301823] BUG: unable to handle kernel paging request at f8e7438c
    [11812.301845] IP: [<f8e38445>] usb_serial_disconnect+0xb5/0x100 [usbserial]
    [11812.301871] *pde = 357ef067 *pte = 00000000
    [11812.301957] Oops: 0000 [#1] PREEMPT SMP
    [11812.301983] Modules linked in: usbserial(-) [last unloaded: pl2303]
    [11812.302008]
    [11812.302019] Pid: 1323, comm: modprobe Tainted: G W 3.4.0-rc7+ #101 Dell Inc. Vostro 1520/0T816J
    [11812.302115] EIP: 0060:[<f8e38445>] EFLAGS: 00010246 CPU: 1
    [11812.302130] EIP is at usb_serial_disconnect+0xb5/0x100 [usbserial]
    [11812.302141] EAX: f508a180 EBX: f508a180 ECX: 00000000 EDX: f8e74300
    [11812.302151] ESI: f5050800 EDI: 00000001 EBP: f5141e78 ESP: f5141e58
    [11812.302160] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
    [11812.302170] CR0: 8005003b CR2: f8e7438c CR3: 34848000 CR4: 000007d0
    [11812.302180] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
    [11812.302189] DR6: ffff0ff0 DR7: 00000400
    [11812.302199] Process modprobe (pid: 1323, ti=f5140000 task=f61e2bc0 task.ti=f5140000)
    [11812.302209] Stack:
    [11812.302216] f8e3be0f f8e3b29c f8e3ae00 00000000 f513641c f5136400 f513641c f507a540
    [11812.302325] f5141e98 c133d2c1 00000000 00000000 f509c400 f513641c f507a590 f5136450
    [11812.302372] f5141ea8 c12f0344 f513641c f507a590 f5141ebc c12f0c67 00000000 f507a590
    [11812.302419] Call Trace:
    [11812.302439] [<c133d2c1>] usb_unbind_interface+0x51/0x190
    [11812.302456] [<c12f0344>] __device_release_driver+0x64/0xb0
    [11812.302469] [<c12f0c67>] driver_detach+0x97/0xa0
    [11812.302483] [<c12f001c>] bus_remove_driver+0x6c/0xe0
    [11812.302500] [<c145938d>] ? __mutex_unlock_slowpath+0xcd/0x140
    [11812.302514] [<c12f0ff9>] driver_unregister+0x49/0x80
    [11812.302528] [<c1457df6>] ? printk+0x1d/0x1f
    [11812.302540] [<c133c50d>] usb_deregister+0x5d/0xb0
    [11812.302557] [<f8e37c55>] ? usb_serial_deregister+0x45/0x50 [usbserial]
    [11812.302575] [<f8e37c8d>] usb_serial_deregister_drivers+0x2d/0x40 [usbserial]
    [11812.302593] [<f8e3a6e2>] usb_serial_generic_deregister+0x12/0x20 [usbserial]
    [11812.302611] [<f8e3acf0>] usb_serial_exit+0x8/0x32 [usbserial]
    [11812.302716] [<c1080b48>] sys_delete_module+0x158/0x260
    [11812.302730] [<c110594e>] ? mntput+0x1e/0x30
    [11812.302746] [<c145c3c3>] ? sysenter_exit+0xf/0x18
    [11812.302746] [<c107777c>] ? trace_hardirqs_on_caller+0xec/0x170
    [11812.302746] [<c145c390>] sysenter_do_call+0x12/0x36
    [11812.302746] Code: 24 02 00 00 e8 dd f3 20 c8 f6 86 74 02 00 00 02 74 b4 8d 86 4c 02 00 00 47 e8 78 55 4b c8 0f b6 43 0e 39 f8 7f a9 8b 53 04 89 d8 <ff> 92 8c 00 00 00 89 d8 e8 0e ff ff ff 8b 45 f0 c7 44 24 04 2f
    [11812.302746] EIP: [<f8e38445>] usb_serial_disconnect+0xb5/0x100 [usbserial] SS:ESP 0068:f5141e58
    [11812.302746] CR2: 00000000f8e7438c

    Fix by only evaluating serial drivers pointing back to the
    USB driver we are currently probing. This still allows two
    or more drivers to match the same device, running their
    serial driver probes to sort out which one to use.

    Signed-off-by: Bjørn Mork <bjorn@mork.no>
    Reviewed-by: Felipe Balbi <balbi@ti.com>
    Tested-by: Johan Hovold <jhovold@gmail.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    drivers/usb/serial/usb-serial.c | 6 ++++--
    1 file changed, 4 insertions(+), 2 deletions(-)

    diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
    index 6a1b609..6e8c527 100644
    --- a/drivers/usb/serial/usb-serial.c
    +++ b/drivers/usb/serial/usb-serial.c
    @@ -659,12 +659,14 @@ exit:
    static struct usb_serial_driver *search_serial_device(
    struct usb_interface *iface)
    {
    - const struct usb_device_id *id;
    + const struct usb_device_id *id = NULL;
    struct usb_serial_driver *drv;
    + struct usb_driver *driver = to_usb_driver(iface->dev.driver);

    /* Check if the usb id matches a known device */
    list_for_each_entry(drv, &usb_serial_driver_list, driver_list) {
    - id = get_iface_id(drv, iface);
    + if (drv->usb_driver == driver)
    + id = get_iface_id(drv, iface);
    if (id)
    return drv;
    }

    --
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