回复: KASAN: use-after-free Read in service_outstanding_interrupt
From: Zhang, Qiang <hidden>
Date: 2021-01-05 04:51:52
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________________________________________ 发件人: Oliver Neukum [off-list ref] 发送时间: 2021年1月5日 0:28 收件人: syzbot; 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 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=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
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_head device_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_descriptor
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))
quoted hunk ↗ jump to hunk
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