linux-kernel - Re: KASAN: use-after-free Read in usbhid

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Pine.LNX.4.44L0.2004182158020.26218-100000@netrider.rowland.org>
Date:   Sat, 18 Apr 2020 22:16:32 -0400 (EDT)
From:   Alan Stern <stern@...land.harvard.edu>
To:     Julian Squires <julian@...ht.net>,
        Hans de Goede <hdegoede@...hat.com>,
        Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        syzbot <syzbot+7bf5a7b0f0a1f9446f4c@...kaller.appspotmail.com>
cc:     linux-input@...r.kernel.org, <andreyknvl@...gle.com>,
        <gregkh@...uxfoundation.org>, <ingrassia@...genesys.com>,
        Kernel development list <linux-kernel@...r.kernel.org>,
        USB list <linux-usb@...r.kernel.org>,
        <syzkaller-bugs@...glegroups.com>
Subject: Re: KASAN: use-after-free Read in usbhid_close (3)

linux-input people:

syzbot has found a bug related to USB/HID/input, and I have narrowed it
down to the wacom driver.  As far as I can tell, the problem is caused
the fact that drivers/hid/wacom_sys.c calls input_register_device()
in several places, but it never calls input_unregister_device().

I know very little about the input subsystem, but this certainly seems 
like a bug.

When the device is unplugged, the disconnect pathway doesn't call
hid_hw_close().  That routine doesn't get called until the user closes
the device file (which can be long after the device is gone and
hid_hw_stop() has run).  Then usbhid_close() gets a use-after-free
error when it tries to access data structures that were deallocated by
usbhid_stop().  No doubt there are other problems too, but this is
the one that syzbot found.

Can any of you help fix this?  Thanks.

Alan Stern