lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20221113080558.GA5854@ubuntu>
Date:   Sun, 13 Nov 2022 00:05:58 -0800
From:   Hyunwoo Kim <imv4bel@...il.com>
To:     Eli Billauer <eli.billauer@...il.com>
Cc:     gregkh@...uxfoundation.org, arnd@...db.de,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        stern@...land.harvard.edu, imv4bel@...il.com
Subject: Re: [PATCH v2] char: xillybus: Prevent use-after-free due to race
 condition

Dear,

Sorry for the late review.

This patch cannot prevent the UAF scenario I presented:
```
                cpu0                                                cpu1
       1. xillyusb_open()
          mutex_lock(&kref_mutex);    // unaffected lock
          xillybus_find_inode()
          mutex_lock(&unit_mutex);
          unit = iter;
          mutex_unlock(&unit_mutex);
                                                             2. xillyusb_disconnect()
                                                                xillybus_cleanup_chrdev()
                                                                mutex_lock(&unit_mutex);
                                                                kfree(unit);
                                                                mutex_unlock(&unit_mutex);
       3. *private_data = unit->private_data;   // UAF

```

This is a UAF for 'unit', not a UAF for 'xdev'.
So, the added 'kref_mutex' has no effect.


Regards,
Hyunwoo Kim

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ