CVE-2021-47634— Linux kernel 安全漏洞
一分钟漏洞结论
影响对象
Linux Linux
利用判断
尚无明确在野利用证据，仍需结合暴露面评估
建议动作
优先检查厂商安全公告和参考链接中的修复版本；无法立即升级时，限制受影响服务暴露并加强监测。
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于ctrl_cdev_ioctl和ubi_cdev_ioctl之间的竞争条件。
影响版本矩阵 36
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | 714fb87e8bc05ff78255afc0dca981e8c5242785< f149b1bd213820363731aa119e5011ca892a2aac |
affected |
714fb87e8bc05ff78255afc0dca981e8c5242785< a8ecee49259f8f78d91ddb329ab2be7e6fd01974 |
affected | ||
714fb87e8bc05ff78255afc0dca981e8c5242785< d727fd32cbd1abf3465f607021bc9c746f17b5a8 |
affected | ||
714fb87e8bc05ff78255afc0dca981e8c5242785< 432b057f8e847ae5a2306515606f8d2defaca178 |
affected | ||
714fb87e8bc05ff78255afc0dca981e8c5242785< 1a3f1cf87054833242fcd0218de0481cf855f888 |
affected | ||
714fb87e8bc05ff78255afc0dca981e8c5242785< c32fe764191b8ae8b128588beb96e3718d9179d8 |
affected | ||
714fb87e8bc05ff78255afc0dca981e8c5242785< 5f9e9c223e48c264241d2f34d0bfc29e5fcb5c1b |
affected | ||
714fb87e8bc05ff78255afc0dca981e8c5242785< 3cbf0e392f173ba0ce425968c8374a6aa3e90f2e |
affected | ||
| … +28 条更多 | |||
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一、 漏洞 CVE-2021-47634 基础信息
漏洞信息
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Vulnerability Title
ubi: Fix race condition between ctrl_cdev_ioctl and ubi_cdev_ioctl
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
ubi: Fix race condition between ctrl_cdev_ioctl and ubi_cdev_ioctl
Hulk Robot reported a KASAN report about use-after-free:
==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0x13d/0x160
Read of size 8 at addr ffff888035e37d98 by task ubiattach/1385
[...]
Call Trace:
klist_dec_and_del+0xa7/0x4a0
klist_put+0xc7/0x1a0
device_del+0x4d4/0xed0
cdev_device_del+0x1a/0x80
ubi_attach_mtd_dev+0x2951/0x34b0 [ubi]
ctrl_cdev_ioctl+0x286/0x2f0 [ubi]
Allocated by task 1414:
device_add+0x60a/0x18b0
cdev_device_add+0x103/0x170
ubi_create_volume+0x1118/0x1a10 [ubi]
ubi_cdev_ioctl+0xb7f/0x1ba0 [ubi]
Freed by task 1385:
cdev_device_del+0x1a/0x80
ubi_remove_volume+0x438/0x6c0 [ubi]
ubi_cdev_ioctl+0xbf4/0x1ba0 [ubi]
[...]
==================================================================
The lock held by ctrl_cdev_ioctl is ubi_devices_mutex, but the lock held
by ubi_cdev_ioctl is ubi->device_mutex. Therefore, the two locks can be
concurrent.
ctrl_cdev_ioctl contains two operations: ubi_attach and ubi_detach.
ubi_detach is bug-free because it uses reference counting to prevent
concurrency. However, uif_init and uif_close in ubi_attach may race with
ubi_cdev_ioctl.
uif_init will race with ubi_cdev_ioctl as in the following stack.
cpu1 cpu2 cpu3
_______________________|________________________|______________________
ctrl_cdev_ioctl
ubi_attach_mtd_dev
uif_init
ubi_cdev_ioctl
ubi_create_volume
cdev_device_add
ubi_add_volume
// sysfs exist
kill_volumes
ubi_cdev_ioctl
ubi_remove_volume
cdev_device_del
// first free
ubi_free_volume
cdev_del
// double free
cdev_device_del
And uif_close will race with ubi_cdev_ioctl as in the following stack.
cpu1 cpu2 cpu3
_______________________|________________________|______________________
ctrl_cdev_ioctl
ubi_attach_mtd_dev
uif_init
ubi_cdev_ioctl
ubi_create_volume
cdev_device_add
ubi_debugfs_init_dev
//error goto out_uif;
uif_close
kill_volumes
ubi_cdev_ioctl
ubi_remove_volume
cdev_device_del
// first free
ubi_free_volume
// double free
The cause of this problem is that commit 714fb87e8bc0 make device
"available" before it becomes accessible via sysfs. Therefore, we
roll back the modification. We will fix the race condition between
ubi device creation and udev by removing ubi_get_device in
vol_attribute_show and dev_attribute_show.This avoids accessing
uninitialized ubi_devices[ubi_num].
ubi_get_device is used to prevent devices from being deleted during
sysfs execution. However, now kernfs ensures that devices will not
be deleted before all reference counting are released.
The key process is shown in the following stack.
device_del
device_remove_attrs
device_remove_groups
sysfs_remove_groups
sysfs_remove_group
remove_files
kernfs_remove_by_name
kernfs_remove_by_name_ns
__kernfs_remove
kernfs_drain
来源: CVE Program / CVE List V5
CVSS Information
N/A
来源: CVE Program / CVE List V5
Vulnerability Type
N/A
来源: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于ctrl_cdev_ioctl和ubi_cdev_ioctl之间的竞争条件。
来源: 中国国家信息安全漏洞库 CNNVD
CVSS Information
N/A
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Type
N/A
来源: 中国国家信息安全漏洞库 CNNVD
受影响产品
二、漏洞 CVE-2021-47634 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2021-47634 补丁与修复 (8)
同批安全公告 · Linux · 2025-02-26 · 共 706 条
| CVE-2022-49149 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49280 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49093 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49094 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49356 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49407 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49418 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49561 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49362 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49194 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49260 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49201 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49058 | 9.1 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2022-49328 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2022-49238 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2022-49471 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2022-49159 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2022-49500 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2022-49479 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2022-49519 | 8.8 HIGH | Linux kernel 安全漏洞 |
显示前 20 条，共 706 条。 查看全部 → →
IV. Related Vulnerabilities
V. Comments for CVE-2021-47634
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