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authorOliver Neukum <oneukum@suse.com>2019-08-08 16:21:19 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-08-15 14:49:16 +0200
commitc52873e5a1ef72f845526d9f6a50704433f9c625 (patch)
tree136da6da0627fede8a7afd52da66423eca351d48 /drivers
parent303911cfc5b95d33687d9046133ff184cf5043ff (diff)
downloadlinux-c52873e5a1ef72f845526d9f6a50704433f9c625.tar.bz2
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.c12
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)) {