在 Linux 内核中发现了一个名为 “Stack Clash” 的严重安全问题，攻击者能够利用它来破坏内存数据并执行任意代码。攻击者可以利用这个及另一个漏洞来执行任意代码并获得管理帐户（root）权限。

在 Linux 中该如何解决这个问题？

Qualys 研究实验室在 GNU C Library（CVE-2017-1000366）的动态链接器中发现了许多问题，它们通过与 Linux 内核内的堆栈冲突来允许本地特权升级。这个 bug 影响到了 i386 和 amd64 上的 Linux、OpenBSD、NetBSD、FreeBSD 和 Solaris。攻击者可以利用它来破坏内存数据并执行任意代码。

什么是 CVE-2017-1000364 bug？

来自 RHN：

在用户空间二进制文件的堆栈中分配内存的方式发现了一个缺陷。如果堆（或不同的内存区域）和堆栈内存区域彼此相邻，则攻击者可以使用此缺陷跳过堆栈保护区域，从而导致进程堆栈或相邻内存区域的受控内存损坏，从而增加其系统权限。有一个在内核中减轻这个漏洞的方法，将堆栈保护区域大小从一页增加到 1 MiB，从而使成功利用这个功能变得困难。

据原研究文章：

计算机上运行的每个程序都使用一个称为堆栈的特殊内存区域。这个内存区域是特别的，因为当程序需要更多的堆栈内存时，它会自动增长。但是，如果它增长太多，并且与另一个内存区域太接近，程序可能会将堆栈与其他内存区域混淆。攻击者可以利用这种混乱来覆盖其他内存区域的堆栈，或者反过来。

受到影响的 Linux 发行版

1. Red Hat Enterprise Linux Server 5.x
2. Red Hat Enterprise Linux Server 6.x
3. Red Hat Enterprise Linux Server 7.x
4. CentOS Linux Server 5.x
5. CentOS Linux Server 6.x
6. CentOS Linux Server 7.x
7. Oracle Enterprise Linux Server 5.x
8. Oracle Enterprise Linux Server 6.x
9. Oracle Enterprise Linux Server 7.x
10. Ubuntu 17.10
11. Ubuntu 17.04
12. Ubuntu 16.10
13. Ubuntu 16.04 LTS
14. Ubuntu 12.04 ESM (Precise Pangolin)
15. Debian 9 stretch
16. Debian 8 jessie
17. Debian 7 wheezy
18. Debian unstable
19. SUSE Linux Enterprise Desktop 12 SP2
20. SUSE Linux Enterprise High Availability 12 SP2
21. SUSE Linux Enterprise Live Patching 12
22. SUSE Linux Enterprise Module for Public Cloud 12
23. SUSE Linux Enterprise Build System Kit 12 SP2
24. SUSE Openstack Cloud Magnum Orchestration 7
25. SUSE Linux Enterprise Server 11 SP3-LTSS
26. SUSE Linux Enterprise Server 11 SP4
27. SUSE Linux Enterprise Server 12 SP1-LTSS
28. SUSE Linux Enterprise Server 12 SP2
29. SUSE Linux Enterprise Server for Raspberry Pi 12 SP2

我需要重启我的电脑么？

是的，由于大多数服务依赖于 GNU C Library 的动态连接器，并且内核自身需要在内存中重新加载。

我该如何在 Linux 中修复 CVE-2017-1000364？

根据你的 Linux 发行版来输入命令。你需要重启电脑。在应用补丁之前，记下你当前内核的版本：

$ uname -a
$ uname -mrs

示例输出：

Linux 4.4.0-78-generic x86_64

Debian 或者 Ubuntu Linux

输入下面的 apt 命令 / apt-get 命令来应用更新：

$ sudo apt-get update && sudo apt-get upgrade && sudo apt-get dist-upgrade

示例输出：

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
  libc-bin libc-dev-bin libc-l10n libc6 libc6-dev libc6-i386 linux-compiler-gcc-6-x86 linux-headers-4.9.0-3-amd64 linux-headers-4.9.0-3-common linux-image-4.9.0-3-amd64
  linux-kbuild-4.9 linux-libc-dev locales multiarch-support
14 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/62.0 MB of archives.
After this operation, 4,096 B of additional disk space will be used.
Do you want to continue? [Y/n] y
Reading changelogs... Done
Preconfiguring packages ...
(Reading database ... 115123 files and directories currently installed.)
Preparing to unpack .../libc6-i386_2.24-11+deb9u1_amd64.deb ...
Unpacking libc6-i386 (2.24-11+deb9u1) over (2.24-11) ...
Preparing to unpack .../libc6-dev_2.24-11+deb9u1_amd64.deb ...
Unpacking libc6-dev:amd64 (2.24-11+deb9u1) over (2.24-11) ...
Preparing to unpack .../libc-dev-bin_2.24-11+deb9u1_amd64.deb ...
Unpacking libc-dev-bin (2.24-11+deb9u1) over (2.24-11) ...
Preparing to unpack .../linux-libc-dev_4.9.30-2+deb9u1_amd64.deb ...
Unpacking linux-libc-dev:amd64 (4.9.30-2+deb9u1) over (4.9.30-2) ...
Preparing to unpack .../libc6_2.24-11+deb9u1_amd64.deb ...
Unpacking libc6:amd64 (2.24-11+deb9u1) over (2.24-11) ...
Setting up libc6:amd64 (2.24-11+deb9u1) ...
(Reading database ... 115123 files and directories currently installed.)
Preparing to unpack .../libc-bin_2.24-11+deb9u1_amd64.deb ...
Unpacking libc-bin (2.24-11+deb9u1) over (2.24-11) ...
Setting up libc-bin (2.24-11+deb9u1) ...
(Reading database ... 115123 files and directories currently installed.)
Preparing to unpack .../multiarch-support_2.24-11+deb9u1_amd64.deb ...
Unpacking multiarch-support (2.24-11+deb9u1) over (2.24-11) ...
Setting up multiarch-support (2.24-11+deb9u1) ...
(Reading database ... 115123 files and directories currently installed.)
Preparing to unpack .../0-libc-l10n_2.24-11+deb9u1_all.deb ...
Unpacking libc-l10n (2.24-11+deb9u1) over (2.24-11) ...
Preparing to unpack .../1-locales_2.24-11+deb9u1_all.deb ...
Unpacking locales (2.24-11+deb9u1) over (2.24-11) ...
Preparing to unpack .../2-linux-compiler-gcc-6-x86_4.9.30-2+deb9u1_amd64.deb ...
Unpacking linux-compiler-gcc-6-x86 (4.9.30-2+deb9u1) over (4.9.30-2) ...
Preparing to unpack .../3-linux-headers-4.9.0-3-amd64_4.9.30-2+deb9u1_amd64.deb ...
Unpacking linux-headers-4.9.0-3-amd64 (4.9.30-2+deb9u1) over (4.9.30-2) ...
Preparing to unpack .../4-linux-headers-4.9.0-3-common_4.9.30-2+deb9u1_all.deb ...
Unpacking linux-headers-4.9.0-3-common (4.9.30-2+deb9u1) over (4.9.30-2) ...
Preparing to unpack .../5-linux-kbuild-4.9_4.9.30-2+deb9u1_amd64.deb ...
Unpacking linux-kbuild-4.9 (4.9.30-2+deb9u1) over (4.9.30-2) ...
Preparing to unpack .../6-linux-image-4.9.0-3-amd64_4.9.30-2+deb9u1_amd64.deb ...
Unpacking linux-image-4.9.0-3-amd64 (4.9.30-2+deb9u1) over (4.9.30-2) ...
Setting up linux-libc-dev:amd64 (4.9.30-2+deb9u1) ...
Setting up linux-headers-4.9.0-3-common (4.9.30-2+deb9u1) ...
Setting up libc6-i386 (2.24-11+deb9u1) ...
Setting up linux-compiler-gcc-6-x86 (4.9.30-2+deb9u1) ...
Setting up linux-kbuild-4.9 (4.9.30-2+deb9u1) ...
Setting up libc-l10n (2.24-11+deb9u1) ...
Processing triggers for man-db (2.7.6.1-2) ...
Setting up libc-dev-bin (2.24-11+deb9u1) ...
Setting up linux-image-4.9.0-3-amd64 (4.9.30-2+deb9u1) ...
/etc/kernel/postinst.d/initramfs-tools:
update-initramfs: Generating /boot/initrd.img-4.9.0-3-amd64
cryptsetup: WARNING: failed to detect canonical device of /dev/md0
cryptsetup: WARNING: could not determine root device from /etc/fstab
W: initramfs-tools configuration sets RESUME=UUID=054b217a-306b-4c18-b0bf-0ed85af6c6e1
W: but no matching swap device is available.
I: The initramfs will attempt to resume from /dev/md1p1
I: (UUID=bf72f3d4-3be4-4f68-8aae-4edfe5431670)
I: Set the RESUME variable to override this.
/etc/kernel/postinst.d/zz-update-grub:
Searching for GRUB installation directory ... found: /boot/grub
Searching for default file ... found: /boot/grub/default
Testing for an existing GRUB menu.lst file ... found: /boot/grub/menu.lst
Searching for splash image ... none found, skipping ...
Found kernel: /boot/vmlinuz-4.9.0-3-amd64
Found kernel: /boot/vmlinuz-3.16.0-4-amd64
Updating /boot/grub/menu.lst ... done

Setting up libc6-dev:amd64 (2.24-11+deb9u1) ...
Setting up locales (2.24-11+deb9u1) ...
Generating locales (this might take a while)...
  en_IN.UTF-8... done
Generation complete.
Setting up linux-headers-4.9.0-3-amd64 (4.9.30-2+deb9u1) ...
Processing triggers for libc-bin (2.24-11+deb9u1) ...

使用 reboot 命令重启桌面/服务器：

$ sudo reboot

Oracle/RHEL/CentOS/Scientific Linux

输入下面的 yum 命令：

$ sudo yum update
$ sudo reboot

Fedora Linux

输入下面的 dnf 命令：

$ sudo dnf update
$ sudo reboot

Suse Enterprise Linux 或者 Opensuse Linux

输入下面的 zypper 命令：

$ sudo zypper patch
$ sudo reboot

SUSE OpenStack Cloud 6

$ sudo zypper in -t patch SUSE-OpenStack-Cloud-6-2017-996=1
$ sudo reboot

SUSE Linux Enterprise Server for SAP 12-SP1

$ sudo zypper in -t patch SUSE-SLE-SAP-12-SP1-2017-996=1
$ sudo reboot

SUSE Linux Enterprise Server 12-SP1-LTSS

$ sudo zypper in -t patch SUSE-SLE-SERVER-12-SP1-2017-996=1
$ sudo reboot

SUSE Linux Enterprise Module for Public Cloud 12

$ sudo zypper in -t patch SUSE-SLE-Module-Public-Cloud-12-2017-996=1
$ sudo reboot

验证

你需要确认你的版本号在 reboot 命令之后改变了。

$ uname -a
$ uname -r
$ uname -mrs

示例输出：

Linux 4.4.0-81-generic x86_64

给 OpenBSD 用户的注意事项

见此页获取更多信息。

给 Oracle Solaris 的注意事项

见此页获取更多信息。

参考

• 堆栈冲突

作者简介:

Vivek Gite

作者是 nixCraft 的创始人，对于 Linux 操作系统/Unix shell脚本有经验丰富的系统管理员和培训师。他曾与全球客户及各行各业，包括 IT、教育、国防和空间研究以及非营利部门合作。在 Twitter、Facebook、Google + 上关注他。

via: https://www.cyberciti.biz/faq/howto-patch-linux-kernel-stack-clash-vulnerability-cve-2017-1000364/

作者：Vivek Gite 译者：geekpi 校对：wxy

本文由 LCTT 原创编译，Linux中国 荣誉推出