diff options
| author | Oliver Neukum <oneukum@suse.com> | 2019-08-08 16:21:19 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-08-15 14:49:16 +0200 |
| commit | c52873e5a1ef72f845526d9f6a50704433f9c625 (patch) | |
| tree | 136da6da0627fede8a7afd52da66423eca351d48 /drivers | |
| parent | 303911cfc5b95d33687d9046133ff184cf5043ff (diff) | |
| download | lwn-c52873e5a1ef72f845526d9f6a50704433f9c625.tar.gz lwn-c52873e5a1ef72f845526d9f6a50704433f9c625.zip | |
usb: cdc-acm: make sure a refcount is taken early enough
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>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/usb/class/cdc-acm.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 183b41753c98..62f4fb9b362f 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1301,10 +1301,6 @@ made_compressed_probe: tty_port_init(&acm->port); acm->port.ops = &acm_port_ops; - 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); @@ -1312,6 +1308,13 @@ 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) @@ -1458,7 +1461,6 @@ 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)) { |