lkml.org 
[lkml]   [2019]   [Aug]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.9 084/103] usb: cdc-acm: make sure a refcount is taken early enough
    Date
    From: Oliver Neukum <oneukum@suse.com>

    commit c52873e5a1ef72f845526d9f6a50704433f9c625 upstream.

    destroy() will decrement the refcount on the interface, so that
    it needs to be taken so early that it never undercounts.

    Fixes: 7fb57a019f94e ("USB: cdc-acm: Fix potential deadlock (lockdep warning)")
    Cc: stable <stable@vger.kernel.org>
    Reported-and-tested-by: syzbot+1b2449b7b5dc240d107a@syzkaller.appspotmail.com
    Signed-off-by: Oliver Neukum <oneukum@suse.com>
    Link: https://lore.kernel.org/r/20190808142119.7998-1-oneukum@suse.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/usb/class/cdc-acm.c | 12 +++++++-----
    1 file changed, 7 insertions(+), 5 deletions(-)

    --- a/drivers/usb/class/cdc-acm.c
    +++ b/drivers/usb/class/cdc-acm.c
    @@ -1264,10 +1264,6 @@ made_compressed_probe:
    if (acm == NULL)
    goto alloc_fail;

    - minor = acm_alloc_minor(acm);
    - if (minor < 0)
    - goto alloc_fail1;
    -
    ctrlsize = usb_endpoint_maxp(epctrl);
    readsize = usb_endpoint_maxp(epread) *
    (quirks == SINGLE_RX_URB ? 1 : 2);
    @@ -1275,6 +1271,13 @@ made_compressed_probe:
    acm->writesize = usb_endpoint_maxp(epwrite) * 20;
    acm->control = control_interface;
    acm->data = data_interface;
    +
    + usb_get_intf(acm->control); /* undone in destruct() */
    +
    + minor = acm_alloc_minor(acm);
    + if (minor < 0)
    + goto alloc_fail1;
    +
    acm->minor = minor;
    acm->dev = usb_dev;
    if (h.usb_cdc_acm_descriptor)
    @@ -1420,7 +1423,6 @@ skip_countries:
    usb_driver_claim_interface(&acm_driver, data_interface, acm);
    usb_set_intfdata(data_interface, acm);

    - usb_get_intf(control_interface);
    tty_dev = tty_port_register_device(&acm->port, acm_tty_driver, minor,
    &control_interface->dev);
    if (IS_ERR(tty_dev)) {

    \
     
     \ /
      Last update: 2019-08-22 19:56    [W:4.502 / U:0.072 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site