CVE-2021-46989— 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，该漏洞源于如果目录文件中的第一个盘区记录已满，则会从盘区溢出文件中分配新的记录。
影响版本矩阵 14
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | 31651c607151f1034cfb57e5a78678bea54c362b< 52dde855663e5db824af51db39b5757d2ef3e28a |
affected |
31651c607151f1034cfb57e5a78678bea54c362b< c451a6bafb5f422197d31536f82116aed132b72c |
affected | ||
31651c607151f1034cfb57e5a78678bea54c362b< adbd8a2a8cc05d9e501f93e5c95c59307874cc99 |
affected | ||
31651c607151f1034cfb57e5a78678bea54c362b< c477f62db1a0c0ecaa60a29713006ceeeb04b685 |
affected | ||
31651c607151f1034cfb57e5a78678bea54c362b< 97314e45aa1223a42d60256a62c5d9af54baf446 |
affected | ||
31651c607151f1034cfb57e5a78678bea54c362b< c3187cf32216313fb316084efac4dab3a8459b1d |
affected | ||
4.19 |
affected | ||
< 4.19 |
unaffected | ||
| … +6 条更多 | |||
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一、 漏洞 CVE-2021-46989 基础信息
漏洞信息
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Vulnerability Title
hfsplus: prevent corruption in shrinking truncate
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
hfsplus: prevent corruption in shrinking truncate
I believe there are some issues introduced by commit 31651c607151
("hfsplus: avoid deadlock on file truncation")
HFS+ has extent records which always contains 8 extents. In case the
first extent record in catalog file gets full, new ones are allocated from
extents overflow file.
In case shrinking truncate happens to middle of an extent record which
locates in extents overflow file, the logic in hfsplus_file_truncate() was
changed so that call to hfs_brec_remove() is not guarded any more.
Right action would be just freeing the extents that exceed the new size
inside extent record by calling hfsplus_free_extents(), and then check if
the whole extent record should be removed. However since the guard
(blk_cnt > start) is now after the call to hfs_brec_remove(), this has
unfortunate effect that the last matching extent record is removed
unconditionally.
To reproduce this issue, create a file which has at least 10 extents, and
then perform shrinking truncate into middle of the last extent record, so
that the number of remaining extents is not under or divisible by 8. This
causes the last extent record (8 extents) to be removed totally instead of
truncating into middle of it. Thus this causes corruption, and lost data.
Fix for this is simply checking if the new truncated end is below the
start of this extent record, making it safe to remove the full extent
record. However call to hfs_brec_remove() can't be moved to it's previous
place since we're dropping ->tree_lock and it can cause a race condition
and the cached info being invalidated possibly corrupting the node data.
Another issue is related to this one. When entering into the block
(blk_cnt > start) we are not holding the ->tree_lock. We break out from
the loop not holding the lock, but hfs_find_exit() does unlock it. Not
sure if it's possible for someone else to take the lock under our feet,
but it can cause hard to debug errors and premature unlocking. Even if
there's no real risk of it, the locking should still always be kept in
balance. Thus taking the lock now just before the check.
来源: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
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，该漏洞源于如果目录文件中的第一个盘区记录已满，则会从盘区溢出文件中分配新的记录。
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-2021-46989 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2021-46989 其他参考 (4)
同批安全公告 · Linux · 2024-02-28 · 共 86 条
| CVE-2021-47013 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2021-47036 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2021-46999 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2021-47035 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-47017 | 8.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-47049 | 8.4 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-47014 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2020-36785 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-47040 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-47048 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-46984 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-46993 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-46998 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-46992 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-46977 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-47012 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-47011 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2020-36787 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-47041 | 7.5 HIGH | Linux kernel 安全漏洞 |
| CVE-2021-46983 | 7.5 HIGH | Linux kernel 安全漏洞 |
显示前 20 条，共 86 条。 查看全部 → →
IV. Related Vulnerabilities
V. Comments for CVE-2021-46989
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