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Date: Sat, 18 Apr 2020 16:20:17 -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 Sat, 18 Apr 2020, syzbot wrote:
> Hello,
>
> syzbot has tested the proposed patch but the reproducer still triggered crash:
> WARNING in usbhid_stop
>
> usb 6-1: USB disconnect, device number 2
> usbhid 6-1:0.0: Stop: 0 0 0
> ------------[ cut here ]------------
> usbhid 6-1:0.0: Stop while open = 1
Okay, now we're getting somewhere. That "Stop: 0 0 0" is unexpected.
Let's probe the starting part of the close pathway more closely.
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 +1199,11 @@ static void usbhid_stop(struct hid_devic
if (WARN_ON(!usbhid))
return;
+ dev_info(&usbhid->intf->dev, "Stop: %d %d %d %d\n",
+ hid->alan1, hid->alan2, hid->alan3, hid->alan4);
+ if (hid->alan_open > 0)
+ dev_WARN(&usbhid->intf->dev, "Stop while open = %d\n",
+ hid->alan_open);
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->alan3;
hidinput_cleanup_battery(hid);
list_for_each_entry_safe(hidinput, next, &hid->inputs, list) {
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"
@@ -2258,6 +2259,11 @@ EXPORT_SYMBOL(input_register_device);
*/
void input_unregister_device(struct input_dev *dev)
{
+ struct hid_device *hid;
+
+ hid = dev->hid;
+ if (hid)
+ ++hid->alan4;
if (dev->devres_managed) {
WARN_ON(devres_destroy(dev->dev.parent,
devm_input_device_unregister,
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, alan4;
};
#define to_hid_device(pdev) \
Index: usb-devel/include/linux/input.h
===================================================================
--- usb-devel.orig/include/linux/input.h
+++ usb-devel/include/linux/input.h
@@ -22,6 +22,7 @@
#include <linux/mod_devicetable.h>
struct input_dev_poller;
+struct hid_device;
/**
* struct input_value - input value representation
@@ -129,6 +130,7 @@ enum input_clock_type {
* by a driver
*/
struct input_dev {
+ struct hid_device *hid;
const char *name;
const char *phys;
const char *uniq;
Index: usb-devel/drivers/hid/wacom_sys.c
===================================================================
--- usb-devel.orig/drivers/hid/wacom_sys.c
+++ usb-devel/drivers/hid/wacom_sys.c
@@ -2017,6 +2017,7 @@ static struct input_dev *wacom_allocate_
if (!input_dev)
return NULL;
+ input_dev->hid = hdev;
input_dev->name = wacom_wac->features.name;
input_dev->phys = hdev->phys;
input_dev->dev.parent = &hdev->dev;
Index: usb-devel/drivers/hid/hid-core.c
===================================================================
--- usb-devel.orig/drivers/hid/hid-core.c
+++ usb-devel/drivers/hid/hid-core.c
@@ -2001,6 +2001,7 @@ EXPORT_SYMBOL_GPL(hid_connect);
void hid_disconnect(struct hid_device *hdev)
{
+ ++hdev->alan2;
device_remove_file(&hdev->dev, &dev_attr_country);
if (hdev->claimed & HID_CLAIMED_INPUT)
hidinput_disconnect(hdev);
@@ -2050,6 +2051,7 @@ EXPORT_SYMBOL_GPL(hid_hw_start);
*/
void hid_hw_stop(struct hid_device *hdev)
{
+ ++hdev->alan1;
hid_disconnect(hdev);
hdev->ll_driver->stop(hdev);
}
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