Re: KASAN: use-after-free Read in service_outstanding_interrupt

From: Oliver Neukum <oneukum@suse.com>
To: syzbot <syzbot+9e04e2df4a32fb661daf@syzkaller.appspotmail.com>,
	andreyknvl@google.com, gregkh@linuxfoundation.org,
	gustavoars@kernel.org, ingrassia@epigenesys.com,
	lee.jones@linaro.org, linux-kernel@vger.kernel.org,
	linux-usb@vger.kernel.org, penguin-kernel@I-love.SAKURA.ne.jp,
	syzkaller-bugs@googlegroups.com
Subject: Re: KASAN: use-after-free Read in service_outstanding_interrupt
Date: Mon, 04 Jan 2021 17:28:21 +0100	[thread overview]
Message-ID: <6a56df508f597d38746878e80e1f159a556d3152.camel@suse.com> (raw)
In-Reply-To: <000000000000994d2a05b6b49959@google.com>

Am Donnerstag, den 17.12.2020, 19:21 -0800 schrieb syzbot:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    5e60366d Merge tag 'fallthrough-fixes-clang-5.11-rc1' of g..
> git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
> console output: https://syzkaller.appspot.com/x/log.txt?x=12c5b623500000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5cea7506b7139727
> dashboard link: https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf
> compiler:       gcc (GCC) 10.1.0-syz 20200507
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=175adf07500000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1672680f500000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+9e04e2df4a32fb661daf@syzkaller.appspotmail.com

#syz test: https://github.com/google/kasan.git  5e60366d

From f51e3c5a202f3abc805edd64b21a68d29dd9d60e Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.com>
Date: Mon, 4 Jan 2021 17:26:33 +0100
Subject: [PATCH] cdc-wdm: poison URBs upon disconnect

We have a chicken and egg issue between interrupt and work.
This should break the cycle.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/usb/class/cdc-wdm.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 02d0cfd23bb2..14eddda35280 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -324,9 +324,9 @@ static void wdm_int_callback(struct urb *urb)
 static void kill_urbs(struct wdm_device *desc)
 {
 	/* the order here is essential */
-	usb_kill_urb(desc->command);
-	usb_kill_urb(desc->validity);
-	usb_kill_urb(desc->response);
+	usb_poison_urb(desc->command);
+	usb_poison_urb(desc->validity);
+	usb_poison_urb(desc->response);
 }
 
 static void free_urbs(struct wdm_device *desc)
-- 
2.26.2


