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：4.19.140,4.19.194,4.19.90,5.10.0,6.1.0,6.1.14,6.1.19,6.1.5,6.1.6,6.1.8,6.4.0,6.6.0
 CVSS V2.0分值：
  BaseScore：0.0 Low
  Vector：CVSS：2.0/
 漏洞简述：
  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.
 漏洞公开时间：2024-05-22 15:15:11
 漏洞创建时间：2024-05-22 16:28:28
 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 |
| ------- | -------- | -------- |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a |  |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525 |  |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca |  |
| suse_bugzilla | http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-47461 | https://bugzilla.suse.com/show_bug.cgi?id=1225249 |
| suse_bugzilla | https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2021/CVE-2021-47461.mbox | https://bugzilla.suse.com/show_bug.cgi?id=1225249 |
| suse_bugzilla | https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525 | https://bugzilla.suse.com/show_bug.cgi?id=1225249 |
| suse_bugzilla | https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a | https://bugzilla.suse.com/show_bug.cgi?id=1225249 |
| suse_bugzilla | https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca | https://bugzilla.suse.com/show_bug.cgi?id=1225249 |
| suse_bugzilla | https://www.cve.org/CVERecord?id=CVE-2021-47461 | https://bugzilla.suse.com/show_bug.cgi?id=1225249 |
| suse_bugzilla | https://bugzilla.redhat.com/show_bug.cgi?id=2282896 | https://bugzilla.suse.com/show_bug.cgi?id=1225249 |
| redhat_bugzilla | https://lore.kernel.org/linux-cve-announce/2024052225-CVE-2021-47461-a472@gregkh/T | https://bugzilla.redhat.com/show_bug.cgi?id=2282896 |
| ubuntu | https://www.cve.org/CVERecord?id=CVE-2021-47461 | https://ubuntu.com/security/CVE-2021-47461 |
| ubuntu | https://git.kernel.org/linus/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca (5.15-rc7) | https://ubuntu.com/security/CVE-2021-47461 |
| ubuntu | https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525 | https://ubuntu.com/security/CVE-2021-47461 |
| ubuntu | https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a | https://ubuntu.com/security/CVE-2021-47461 |
| ubuntu | https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca | https://ubuntu.com/security/CVE-2021-47461 |
| ubuntu | https://nvd.nist.gov/vuln/detail/CVE-2021-47461 | https://ubuntu.com/security/CVE-2021-47461 |
| ubuntu | https://launchpad.net/bugs/cve/CVE-2021-47461 | https://ubuntu.com/security/CVE-2021-47461 |
| ubuntu | https://security-tracker.debian.org/tracker/CVE-2021-47461 | https://ubuntu.com/security/CVE-2021-47461 |

</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  |
| ------- | -------- | ------- | -------- | --------- |
| linux |  | https://git.kernel.org/linus/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca | https://git.kernel.org/linus/63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 | ubuntu |

</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:L/PR:L/UI:N/S:U/C:N/I:N/A:H
 受影响版本排查(受影响/不受影响)：
  1.openEuler-20.03-LTS-SP4(4.19.90):不受影响
2.openEuler-22.03-LTS-SP1(5.10.0):不受影响
3.openEuler-22.03-LTS-SP3(5.10.0):不受影响
4.openEuler-22.03-LTS-SP4(5.10.0):不受影响
5.master(6.1.0):不受影响
6.openEuler-24.03-LTS(6.6.0):不受影响
7.openEuler-24.03-LTS-Next(6.6.0):不受影响

修复是否涉及abi变化(是/否)：
  1.openEuler-20.03-LTS-SP4(4.19.90):否
2.openEuler-22.03-LTS-SP1(5.10.0):否
3.openEuler-22.03-LTS-SP3(5.10.0):否
4.master(6.1.0):否
5.openEuler-24.03-LTS(6.6.0):否
6.openEuler-24.03-LTS-Next(6.6.0):否
7.openEuler-22.03-LTS-SP4(5.10.0):否

@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.**