From: ChenXiaoSong <chenxiaosong2@huawei.com>
To: Hyunwoo Kim <imv4bel@gmail.com>
Cc: <steve.glendinning@shawell.net>, <deller@gmx.de>,
<linux-fbdev@vger.kernel.org>, <dri-devel@lists.freedesktop.org>,
<imv4bel@gmail.com>, "zhangxiaoxu (A)" <zhangxiaoxu5@huawei.com>,
<yangerkun@huawei.com>
Subject: Question about patch "fbdev: smscufx: Fix use-after-free in ufx_ops_open()"
Date: Tue, 11 Oct 2022 22:13:02 +0800 [thread overview]
Message-ID: <363cdfe4-f54d-0ce4-2f03-bcfe998deeef@huawei.com> (raw)
Hi Hyunwoo:
[patch "fbdev: smscufx: Fix use-after-free in
ufx_ops_open()"](https://lore.kernel.org/all/20220925133243.GA383897@ubuntu/T/)
fix [CVE-2022-41849](https://nvd.nist.gov/vuln/detail/CVE-2022-41849).
If the UAF scenarios is as follows, it seems that [fix path
v3](https://lore.kernel.org/all/20220925133243.GA383897@ubuntu/T/) will
not avoid race contidion of krefs:
```
cpu0 | cpu1
-------------------------------------|---------------------------------------------------
1. open() |
ufx_ops_open() |
-------------------------------------|---------------------------------------------------
| 2. ufx_usb_disconnect()
| dev->virtualized = true;
| atomic_set()
| usb_set_intfdata()
|
| 3. if (dev->fb_count == 0)
| schedule_delayed_work()
| kref_put() <- kref count : 1
| kref_put() <- kref count : 0
| ufx_free()
| kfree(dev);
-------------------------------------|---------------------------------------------------
4. if (dev->virtualized) <==== UAF |
```
Did I misunderstand the UAF scenarios ?
next reply other threads:[~2022-10-11 14:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-11 14:13 ChenXiaoSong [this message]
2022-10-11 15:34 ` Question about patch "fbdev: smscufx: Fix use-after-free in ufx_ops_open()" Hyunwoo Kim
2022-10-20 20:05 ` Hyunwoo Kim
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