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

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Date:   Sat, 25 Apr 2020 19:31:21 +0200
From:   Oliver Neukum <oneukum@...e.com>
To:     Alan Stern <stern@...land.harvard.edu>
Cc:     Pete Zaitcev <zaitcev@...hat.com>, Hillf Danton <hdanton@...a.com>,
        syzbot <syzbot+be5b5f86a162a6c281e6@...kaller.appspotmail.com>,
        andreyknvl@...gle.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: KASAN: use-after-free Read in usblp_bulk_read

Am Donnerstag, den 23.04.2020, 12:29 -0400 schrieb Alan Stern:
> On Thu, 23 Apr 2020, Oliver Neukum wrote:

> The only suspicious thing I see is that usblp_resume() calls 
> handle_bidir() without first acquiring any mutex.  But resume shouldn't 
> race with disconnect.

Right.

> The only other place where read URBs get submitted is under
> usblp_read(), which does acquire the mutex

Right.

>  and checks for disconnection
> while holding it.

Where? It should, but I do not see where it does so.

	Regards
		Oliver

View attachment "0001-usblp-fix-race-between-disconnect-and-read.patch" of type "text/x-patch" (1022 bytes)