Messages in this thread | | | Date | Tue, 06 Aug 2019 07:22:37 -0700 | Subject | Re: Re: possible deadlock in usb_deregister_dev | From | syzbot <> |
| |
> Am Montag, den 05.08.2019, 04:58 -0700 schrieb syzbot: >> Hello,
>> syzbot found the following crash on:
>> HEAD commit: e96407b4 usb-fuzzer: main usb gadget fuzzer driver >> git tree: https://github.com/google/kasan.git usb-fuzzer >> console output: https://syzkaller.appspot.com/x/log.txt?x=13b5bc8a600000 >> kernel config: >> https://syzkaller.appspot.com/x/.config?x=792eb47789f57810 >> dashboard link: >> https://syzkaller.appspot.com/bug?extid=a64a382964bf6c71a9c0 >> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
>> Unfortunately, I don't have any reproducer for this crash yet.
>> IMPORTANT: if you fix the bug, please add the following tag to the >> commit: >> Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com
> #syz test: https://github.com/google/kasan.git e96407b4
This crash does not have a reproducer. I cannot test it.
> From 973e82b3f583113e4d7fe5cd2f918a16022c4e38 Mon Sep 17 00:00:00 2001 > From: Oliver Neukum <oneukum@suse.com> > Date: Tue, 6 Aug 2019 16:17:54 +0200 > Subject: [PATCH] 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: 03f36e885fc26 ("USB: open disconnect race in iowarrior") > Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com > Signed-off-by: Oliver Neukum <oneukum@suse.com> > --- > drivers/usb/misc/iowarrior.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-)
> diff --git a/drivers/usb/misc/iowarrior.c b/drivers/usb/misc/iowarrior.c > index ba05dd80a020..f5bed9f29e56 100644 > --- a/drivers/usb/misc/iowarrior.c > +++ b/drivers/usb/misc/iowarrior.c > @@ -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 , > -- > 2.16.4
| |