CVE-2021-47461

一、漏洞信息
 漏洞编号：[CVE-2021-47461](https://nvd.nist.gov/vuln/detail/CVE-2021-47461)
 漏洞归属组件：[kernel](https://gitee.com/src-openeuler/kernel)
 漏洞归属的版本：5.10.0
 CVSS V3.0分值：
  BaseScore：0.0 None
  Vector：CVSS：3.0/
 漏洞简述：
  A vulnerability classified as problematic has been found in Linux Kernel up to 5.10.75/5.14.14 (Operating System).CWE is classifying the issue as CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.This is going to have an impact on confidentiality, integrity, and availability.Upgrading to version 5.10.76 or 5.14.15 eliminates this vulnerability. Applying the patch 3cda4bfffd4f/149958ecd062/cb185d5f1ebf is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.
 漏洞公开时间：2024-05-22 00:00:00
 漏洞创建时间：2024-05-22 08:28:28
 漏洞详情参考链接：
  https://nvd.nist.gov/vuln/detail/CVE-2021-47461
<details>
<summary>更多参考(点击展开)</summary>

| 参考来源 | 参考链接 | 来源链接 |
| ------- | -------- | -------- |
|  | https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a |  |
|  | https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525 |  |
|  | https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca |  |
|  | https://www.cve.org/CVERecord?id=CVE-2021-47461 |  |
|  | https://git.kernel.org/linus/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca |  |

</details>

漏洞分析指导链接：
  https://gitee.com/openeuler/cve-manager/blob/master/cve-vulner-manager/doc/md/manual.md
 漏洞数据来源:
  openBrain开源漏洞感知系统
 漏洞补丁信息：
  <details>
<summary>详情(点击展开)</summary>

| 影响的包 | 修复版本 | 修复补丁 | 问题引入补丁 | 来源  |
| ------- | -------- | ------- | -------- | --------- |
|  | https://github.com/torvalds/linux/commit/cb185d5f1ebf900f4ae3bf8 | https://github.com/torvalds/linux/commit/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca.patch |  | ljqc |
|  | https://github.com/gregkh/linux/commit/cb185d5f1ebf900f4ae3bf84c | https://github.com/gregkh/linux/commit/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca.patch |  | ljqc |

</details>

二、漏洞分析结构反馈
 影响性分析说明：
    In the Linux kernel, the following vulnerability has been resolved:userfaultfd: fix a race between writeprotect and exit_mmap()A race is possible when a process exits, its VMAs are removed byexit_mmap() and at the same time userfaultfd_writeprotect() is called.The race was detected by KASAN on a development kernel, but it appearsto be possible on vanilla kernels as well.Use mmget_not_zero() to prevent the race as done in other userfaultfdoperations. 
 openEuler评分：
  5.5
 Vector：CVSS：3.0/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:N
 受影响版本排查(受影响/不受影响)：
  1.openEuler-22.03-LTS-SP1:受影响
2.openEuler-22.03-LTS-SP3:受影响
3.openEuler-20.03-LTS-SP1:不受影响
4.openEuler-20.03-LTS-SP4:不受影响
5.openEuler-22.03-LTS:不受影响
6.openEuler-22.03-LTS-SP2:不受影响
7.openEuler-22.03-LTS-SP4:不受影响
8.master:不受影响
9.openEuler-22.03-LTS-Next:不受影响
10.openEuler-24.03-LTS:不受影响
11.openEuler-24.03-LTS-Next:不受影响

修复是否涉及abi变化(是/否)：
  1.openEuler-20.03-LTS-SP1:否
2.openEuler-20.03-LTS-SP4:否
3.openEuler-22.03-LTS:否
4.openEuler-22.03-LTS-SP1:否
5.openEuler-22.03-LTS-SP2:否
6.openEuler-22.03-LTS-SP3:否
7.master:否
8.openEuler-22.03-LTS-Next:否
9.openEuler-24.03-LTS:否
10.openEuler-24.03-LTS-Next:否
11.openEuler-22.03-LTS-SP4:否

原因说明：
  1.master:
2.openEuler-20.03-LTS-SP4:
3.openEuler-22.03-LTS-SP1:
4.openEuler-22.03-LTS-SP3:
5.openEuler-22.03-LTS-SP4:
6.openEuler-24.03-LTS:
7.openEuler-24.03-LTS-Next:
8.openEuler-24.03-LTS-SP1:

@yangyingliang ,@jiaoff ,@guohaocs2c ,@hanjun-guo ,@woqidaideshi ,@newbeats ,@zhangyi089 ,@colyli ,@thundertown ,@htforge ,@chiqijun ,@lengchao ,@zhujianwei001 ,@kylin-mayukun ,@wangxiongfeng ,@wkfxxx ,@SuperSix173 ,@jentlestea ,@oskernel0719 ,@gasonchen 
**issue处理注意事项:** 
**1. 当前issue受影响的分支提交pr时, 须在pr描述中填写当前issue编号进行关联, 否则无法关闭当前issue;**
**2. 模板内容需要填写完整, 无论是受影响或者不受影响都需要填写完整内容,未引入的分支不需要填写, 否则无法关闭当前issue;**
**3. 以下为模板中需要填写完整的内容, 请复制到评论区回复, 注: 内容的标题名称(影响性分析说明, openEuler评分, 受影响版本排查(受影响/不受影响), 修复是否涉及abi变化(是/否))不能省略,省略后cve-manager将无法正常解析填写内容.**
************************************************************************
影响性分析说明:

openEuler评分: (评分和向量)

受影响版本排查(受影响/不受影响): 
1.master(6.1.0):
2.openEuler-20.03-LTS-SP1(4.19.90):
3.openEuler-20.03-LTS-SP4(4.19.90):
4.openEuler-22.03-LTS(5.10.0):
5.openEuler-22.03-LTS-Next(5.10.0):
6.openEuler-22.03-LTS-SP1(5.10.0):
7.openEuler-22.03-LTS-SP2(5.10.0):
8.openEuler-22.03-LTS-SP3(5.10.0):
9.openEuler-22.03-LTS-SP4:
10.openEuler-24.03-LTS:
11.openEuler-24.03-LTS-Next:

修复是否涉及abi变化(是/否)：
1.master(6.1.0):
2.openEuler-20.03-LTS-SP1(4.19.90):
3.openEuler-20.03-LTS-SP4(4.19.90):
4.openEuler-22.03-LTS(5.10.0):
5.openEuler-22.03-LTS-Next(5.10.0):
6.openEuler-22.03-LTS-SP1(5.10.0):
7.openEuler-22.03-LTS-SP2(5.10.0):
8.openEuler-22.03-LTS-SP3(5.10.0):
9.openEuler-22.03-LTS-SP4:
10.openEuler-24.03-LTS:
11.openEuler-24.03-LTS-Next:

-----------------------------------------------------------------------
issue处理具体操作请参考: 
https://gitee.com/openeuler/cve-manager/blob/master/cve-vulner-manager/doc/md/manual.md
pr关联issue具体操作请参考:
https://gitee.com/help/articles/4142

<table><tr><th white-space: nowrap;>参考网址</th> <th white-space: nowrap;>关联pr</th> <th white-space: nowrap;>状态</th> <th white-space: nowrap;>补丁链接</th></tr><tr><td rowspan="1">https://nvd.nist.gov/vuln/detail/CVE-2021-47461</td><td>None</td><td>None</td><td><a href=https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca>https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca</a><br /><a href=https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525>https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525</a><br /><a href=https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a>https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a</a></td></tr><tr><td rowspan="1">https://www.opencve.io/cve/CVE-2021-47461</td><td>None</td><td>None</td><td><a href=https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca>https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca</a><br /><a href=https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525>https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525</a><br /><a href=https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a>https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a</a></td></tr><tr><td>https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2021-47461</td><td></td><td></td><td></td></tr><tr><td rowspan="1">https://security-tracker.debian.org/tracker/CVE-2021-47461</td><td>None</td><td>None</td><td><a href=https://git.kernel.org/linus/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca>https://git.kernel.org/linus/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca</a></td></tr></table>

> 说明：补丁链接仅供初步排查参考，实际可用性请人工再次确认，补丁下载验证可使用[CVE补丁工具](https://gitee.com/openeuler/cve-manager/blob/master/cve-agency-manager/cve_tracking/README.md)。
若补丁不准确，烦请在此issue下评论 '/report-patch 参考网址 补丁链接1,补丁链接2' 反馈正确信息，便于我们不断优化工具，不胜感激。
如 /report-patch https://security-tracker.debian.org/tracker/CVE-2021-3997 https://github.com/systemd/systemd/commit/5b1cf7a9be37e20133c0208005274ce4a5b5c6a1

CVE-2021-47461

影响性分析说明：
In the Linux kernel, the following vulnerability has been resolved:

userfaultfd: fix a race between writeprotect and exit_mmap()

A race is possible when a process exits, its VMAs are removed by
exit_mmap() and at the same time userfaultfd_writeprotect() is called.

The race was detected by KASAN on a development kernel, but it appears
to be possible on vanilla kernels as well.

Use mmget_not_zero() to prevent the race as done in other userfaultfd
operations.

openEuler评分:(评分和向量)
5.5
CVSS: 3.0/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:N

受影响版本排查(受影响/不受影响):
1.openEuler-20.03-LTS-SP1:不受影响
2.openEuler-20.03-LTS-SP4:不受影响
3.openEuler-22.03-LTS:受影响
4.openEuler-22.03-LTS-SP1:受影响
5.openEuler-22.03-LTS-SP2:受影响
6.openEuler-22.03-LTS-SP3:受影响
7.openEuler-22.03-LTS-SP4:不受影响8.master(6.1.0):不受影响
9.openEuler-22.03-LTS-Next:不受影响
10.openEuler-24.03-LTS:不受影响
11.openEuler-24.03-LTS-Next:不受影响

修复是否涉及abi变化(是/否)：
1.openEuler-20.03-LTS-SP1(4.19.90):否
2.openEuler-20.03-LTS-SP4:否
3.openEuler-22.03-LTS:否
4.openEuler-22.03-LTS-SP1:否
5.openEuler-22.03-LTS-SP2:否
6.openEuler-22.03-LTS-SP3:否
7.master(6.1.0):否
8.openEuler-22.03-LTS-Next:否
9.openEuler-24.03-LTS:否
10.openEuler-24.03-LTS-Next:否
11.openEuler-22.03-LTS-SP4:否

@ 经过 cve-manager 解析, 已分析的内容如下表所示:
| 状态  | 需分析 | 内容 |
|:--:|:--:|---------|
|已分析|1.影响性分析说明|In the Linux kernel, the following vulnerability has been resolved:userfaultfd: fix a race between writeprotect and exit_mmap()A race is possible when a process exits, its VMAs are removed byexit_mmap() and at the same time userfaultfd_writeprotect() is called.The race was detected by KASAN on a development kernel, but it appearsto be possible on vanilla kernels as well.Use mmget_not_zero() to prevent the race as done in other userfaultfdoperations.|
|已分析|2.openEulerScore|5.5|
|已分析|3.openEulerVector|AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:N|
|已分析|4.受影响版本排查|openEuler-22.03-LTS:受影响,openEuler-22.03-LTS-SP1:受影响,openEuler-22.03-LTS-SP2:受影响,openEuler-22.03-LTS-SP3:受影响,openEuler-20.03-LTS-SP1:不受影响,openEuler-20.03-LTS-SP4:不受影响,openEuler-22.03-LTS-SP4:不受影响,master:不受影响,openEuler-22.03-LTS-Next:不受影响,openEuler-24.03-LTS:不受影响,openEuler-24.03-LTS-Next:不受影响|
|已分析|5.修复是否涉及abi变化|openEuler-20.03-LTS-SP1:否,openEuler-20.03-LTS-SP4:否,openEuler-22.03-LTS:否,openEuler-22.03-LTS-SP1:否,openEuler-22.03-LTS-SP2:否,openEuler-22.03-LTS-SP3:否,master:否,openEuler-22.03-LTS-Next:否,openEuler-24.03-LTS:否,openEuler-24.03-LTS-Next:否,openEuler-22.03-LTS-SP4:否|

**请确认分析内容的准确性, 确认无误后, 您可以进行后续步骤, 否则您可以继续分析.**