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Message-ID: <Pine.LNX.4.44L0.2004172128290.23070-100000@netrider.rowland.org>
Date: Fri, 17 Apr 2020 21:30:12 -0400 (EDT)
From: Alan Stern <stern@...land.harvard.edu>
To: syzbot <syzbot+7bf5a7b0f0a1f9446f4c@...kaller.appspotmail.com>
cc: andreyknvl@...gle.com, <gregkh@...uxfoundation.org>,
<ingrassia@...genesys.com>, <linux-kernel@...r.kernel.org>,
<linux-usb@...r.kernel.org>, <syzkaller-bugs@...glegroups.com>
Subject: Re: KASAN: use-after-free Read in usbhid_close (3)
On Fri, 17 Apr 2020, syzbot wrote:
> Hello,
>
> syzbot has tested the proposed patch but the reproducer still triggered crash:
> WARNING in usbhid_stop
>
> usb 2-1: USB disconnect, device number 5
> ------------[ cut here ]------------
> usbhid 2-1:0.0: Stop while open (alloc = 1)
Okay, good. usbhid_close() should have been called before this
happened. Let's try tracing the pathway; maybe this will show where it
goes off the rails.
Alan Stern
#syz test: https://github.com/google/kasan.git 0fa84af8
Index: usb-devel/drivers/hid/usbhid/hid-core.c
===================================================================
--- usb-devel.orig/drivers/hid/usbhid/hid-core.c
+++ usb-devel/drivers/hid/usbhid/hid-core.c
@@ -747,6 +747,7 @@ static void usbhid_close(struct hid_devi
return;
hid_cancel_delayed_stuff(usbhid);
+ --hid->alan_open;
usb_kill_urb(usbhid->urbin);
usbhid->intf->needs_remote_wakeup = 0;
}
@@ -1177,6 +1178,7 @@ static int usbhid_start(struct hid_devic
usbhid_set_leds(hid);
device_set_wakeup_enable(&dev->dev, 1);
}
+ ++hid->alan_open;
return 0;
fail:
@@ -1197,6 +1199,10 @@ static void usbhid_stop(struct hid_devic
if (WARN_ON(!usbhid))
return;
+ if (hid->alan_open > 0)
+ dev_WARN(&usbhid->intf->dev, "Stop while open = %d: %d %d %d\n",
+ hid->alan_open,
+ hid->alan1, hid->alan2, hid->alan3);
if (hid->quirks & HID_QUIRK_ALWAYS_POLL) {
clear_bit(HID_IN_POLLING, &usbhid->iofl);
usbhid->intf->needs_remote_wakeup = 0;
Index: usb-devel/drivers/hid/hid-input.c
===================================================================
--- usb-devel.orig/drivers/hid/hid-input.c
+++ usb-devel/drivers/hid/hid-input.c
@@ -1960,6 +1960,7 @@ void hidinput_disconnect(struct hid_devi
{
struct hid_input *hidinput, *next;
+ ++hid->alan1;
hidinput_cleanup_battery(hid);
list_for_each_entry_safe(hidinput, next, &hid->inputs, list) {
Index: usb-devel/drivers/input/evdev.c
===================================================================
--- usb-devel.orig/drivers/input/evdev.c
+++ usb-devel/drivers/input/evdev.c
@@ -23,6 +23,7 @@
#include <linux/major.h>
#include <linux/device.h>
#include <linux/cdev.h>
+#include <linux/hid.h>
#include "input-compat.h"
struct evdev {
@@ -1329,6 +1330,11 @@ static void evdev_mark_dead(struct evdev
static void evdev_cleanup(struct evdev *evdev)
{
struct input_handle *handle = &evdev->handle;
+ struct hid_device *hid;
+
+ hid = (struct hid_device *) input_get_drvdata(evdev->handle.dev);
+ if (hid)
+ ++hid->alan3;
evdev_mark_dead(evdev);
evdev_hangup(evdev);
Index: usb-devel/drivers/input/input.c
===================================================================
--- usb-devel.orig/drivers/input/input.c
+++ usb-devel/drivers/input/input.c
@@ -23,6 +23,7 @@
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/rcupdate.h>
+#include <linux/hid.h>
#include "input-compat.h"
#include "input-poller.h"
@@ -2081,7 +2082,11 @@ static void input_cleanse_bitmasks(struc
static void __input_unregister_device(struct input_dev *dev)
{
struct input_handle *handle, *next;
+ struct hid_device *hid;
+ hid = (struct hid_device *) input_get_drvdata(dev);
+ if (hid)
+ ++hid->alan2;
input_disconnect_device(dev);
mutex_lock(&input_mutex);
Index: usb-devel/include/linux/hid.h
===================================================================
--- usb-devel.orig/include/linux/hid.h
+++ usb-devel/include/linux/hid.h
@@ -618,6 +618,9 @@ struct hid_device { /* device repo
struct list_head debug_list;
spinlock_t debug_list_lock;
wait_queue_head_t debug_wait;
+
+ int alan_open;
+ int alan1, alan2, alan3;
};
#define to_hid_device(pdev) \
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