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usb: iowarrior: fix deadlock on disconnect 

We have to drop the mutex before we close() upon disconnect()
as close() needs the lock. This is safe to do by dropping the
mutex as intfdata is already set to NULL, so open() will fail.

Fixes: 03f36e885f ("USB: open disconnect race in iowarrior")
Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Link: https://lore.kernel.org/r/20190808092728.23417-1-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
alistair/sunxi64-5.4-dsi
Oliver Neukum 2019-08-08 11:27:28 +02:00 committed by Greg Kroah-Hartman
parent 2ca359f4f8
commit c468a8aa79
1 changed files with 4 additions and 3 deletions
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7
drivers/usb/misc/iowarrior.c
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@ -866,19 +866,20 @@ static void iowarrior_disconnect(struct usb_interface *interface)
dev = usb_get_intfdata(interface);
mutex_lock(&iowarrior_open_disc_lock);
usb_set_intfdata(interface, NULL);
/* prevent device read, write and ioctl */
dev->present = 0;
minor = dev->minor;
mutex_unlock(&iowarrior_open_disc_lock);
/* give back our minor - this will call close() locks need to be dropped at this point*/
/* give back our minor */
usb_deregister_dev(interface, &iowarrior_class);
mutex_lock(&dev->mutex);
/* prevent device read, write and ioctl */
dev->present = 0;
mutex_unlock(&dev->mutex);
mutex_unlock(&iowarrior_open_disc_lock);
if (dev->opened) {
/* There is a process that holds a filedescriptor to the device ,