发件人: Oliver Neukum
发送时间: 2021年1月5日 0:28
收件人: syzbot; andreyk...@google.com; gre...@linuxfoundation.org;
gustavo...@kernel.org; ingras...@epigenesys.com; lee.jo...@linaro.org;
linux-kernel@vger.kernel.org; linux-...@vger.kernel.org;
penguin-ker...@i-love.sakura.ne.jp; syzkaller-b...@googlegroups.com
主题: Re: KASAN: use-after-free Read in service_outstanding_interrupt
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=12c5b62350
> 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=175adf0750
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1672680f50
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: >syzbot+9e04e2df4a32fb661...@syzkaller.appspotmail.com
>
>#syz test: https://github.com/google/kasan.git 5e60366d
>
Hello Oliver
this use-after-free still exists，It can be seen from calltrace that it is
usb_device's object has been released when disconnect,
can add a reference count to usb_device's object to avoid this problem
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 508b1c3f8b73..001cb93da6bf 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -106,6 +106,7 @@ struct wdm_device {
struct list_headdevice_list;
int (*manage_power)(struct usb_interface *, int);
+ struct usb_device *usb_dev;
};
static struct usb_driver wdm_driver;
@@ -338,6 +339,7 @@ static void free_urbs(struct wdm_device *desc)
static void cleanup(struct wdm_device *desc)
{
+ usb_put_dev(desc->usb_dev);
kfree(desc->sbuf);
kfree(desc->inbuf);
kfree(desc->orq);
@@ -855,6 +857,7 @@ static int wdm_create(struct usb_interface *intf, struct
usb_endpoint_descripto
r
desc->intf = intf;
INIT_WORK(&desc->rxwork, wdm_rxwork);
INIT_WORK(&desc->service_outs_intr, service_interrupt_work);
+ desc->usb_dev = usb_get_dev(interface_to_usbdev(intf));
rv = -EINVAL;
if (!usb_endpoint_is_int_in(ep))
>From f51e3c5a202f3abc805edd64b21a68d29dd9d60e Mon Sep 17 >00:00:00 2001
>From: Oliver Neukum
>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
>---
>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
