CVE-2026-89768— 文件系统：修复嵌套备份文件的用户路径
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。
以下是该 Linux 内核漏洞描述的中文翻译： 在 Linux 内核中，以下漏洞已得到修复： 文件系统：修复嵌套 backing file 的用户路径问题 函数从 推导应存储在新 backing file 中的路径。当 本身就是一个 backing file 时，这种做法是不正确的。这种情况出现在嵌套的堆叠文件系统中，例如，当一个 overlayfs 挂载的 lowerdir 是另一个 overlayfs 的合并目录（merged directory）时。 自提交 （“fs: 在 backing file 的 f_
影响版本矩阵 16
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | 5b6aa9a843205da92d860e5011a7b29062a76b8f< 88c927a63dc717b6d46b20fe13ea713916e49089 |
affected |
5dfcb15974e7d0f96aca278dd9f1b85df91523ef< c03114634d342648bd34910aa8fb88007e92cc3c |
affected | ||
6af36aeb147a06dea47c49859cd6ca5659aeb987< a35cc21355734e1acb89973d9be90ca8e4c3ed2f |
affected | ||
6af36aeb147a06dea47c49859cd6ca5659aeb987< f2381b546e7e6a35c9fcee0d0ccb6c042a9aeb5d |
affected | ||
41c5b269af8b1f0bffcab7766a793f294ae6764e |
affected | ||
27e795afba0018b0ea9460dbad4bd706d1ba5ee0 |
affected | ||
6.12.95< 6.12.109 |
affected | ||
6.18.38< 6.18.50 |
affected | ||
| … +8 条更多 | |||
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一、 漏洞 CVE-2026-89768 基础信息
漏洞信息
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Vulnerability Title
fs: fix user path of nested backing files
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
fs: fix user path of nested backing files
backing_file_open() derives the path to be stored in the new backing
file from user_file->f_path. This is incorrect when user_file itself
is a backing file, which is the case for nested stacking filesystems,
e.g. overlayfs mounts where the lowerdir of one overlayfs is the merged
directory of another. Since commit def3ae83da02 ("fs: store real path
instead of fake path in backing file f_path") the f_path of a backing
file holds the real path of the intermediate layer, not the path that
the user opened.
Commit 924577e4f6ca ("ovl: Fix nested backing file paths") fixed this
for such configurations by passing file_user_path() from
ovl_open_realfile(). However, commit 6af36aeb147a ("lsm: add
backing_file LSM hooks") changed the first argument of
backing_file_open() from the user path back to the user file and
derived the path from user_file->f_path again, silently re-introducing
the problem.
As a result, files mapped through a nested overlayfs show the wrong
path in /proc/<pid>/maps and in perf/ftrace mmap records. For example,
with two nested overlayfs mounts:
mkdir -p /ovl/{lower,upper,work,merged} /ovl/nested
echo hello > /ovl/lower/foo
mount -t overlay overlay \
-o lowerdir=/ovl/lower,upperdir=/ovl/upper,workdir=/ovl/work \
/ovl/merged
# at least two lowerdirs are needed when upperdir is nonexistent
mount -t overlay overlay \
-o lowerdir=/ovl/merged:/ovl/lower /ovl/nested
mapping /ovl/nested/foo shows a disconnected path instead of the user
path:
# readlink /proc/self/fd/3
/ovl/nested/foo
# grep foo /proc/self/maps
7f6e2c100000-7f6e2c101000 r--s 00000000 00:24 15813027 /foo
The bogus path is derived from the f_path of the intermediate backing
file, whose mount is a private clone that d_path() cannot resolve.
Fix this by using file_user_path(), which returns the outermost
user-visible path for backing files and falls back to
&user_file->f_path for regular files. This restores the behavior of
commit 924577e4f6ca ("ovl: Fix nested backing file paths") for
overlayfs and also fixes the same problem for the other
backing_file_open() callers, fuse passthrough and erofs ishare, when
their user file is itself a backing file.
backing_tmpfile_open() has the same pattern but is not affected: it is
only called by ovl_create_tmpfile() for the upper layer, and another
overlayfs is rejected as upperdir by the DCACHE_OP_REAL check in
ovl_mount_dir_check(), so its user_file can never be a backing file.
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
受影响产品
二、漏洞 CVE-2026-89768 的公开POC
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CVE-2026-89768 其他参考 (4)
同批安全公告 · Linux · 2026-09-11 · 共 431 条
| CVE-2026-89491 | OCFS2集群心跳锁持有期间睡眠漏洞 | |
| CVE-2026-89477 | Linux内核 SCTP 重配置空指针引用漏洞 | |
| CVE-2026-89478 | sctp：移除的传输中丢弃数据块 | |
| CVE-2026-89479 | 内核SCTP模块关联删除后仍处理报文 | |
| CVE-2026-89480 | NVMe-TCP 读取字节数异常拒绝漏洞 | |
| CVE-2026-89482 | NVMe-TCP 数据长度误判漏洞 | |
| CVE-2026-89481 | NVMe/TCP 主机内存泄露漏洞 | |
| CVE-2026-89483 | Linux内核 NVMe驱动 逻辑错误 | |
| CVE-2026-89484 | Linux内核lockd 空指针解引用漏洞 | |
| CVE-2026-89485 | Linux lockd 锁释放时文件指针固定漏洞 | |
| CVE-2026-89486 | IPMI 驱动 _ipmi_destroy_user 释放后使用漏洞 | |
| CVE-2026-89487 | Open vSwitch 数据包丢弃逻辑缺陷 | |
| CVE-2026-89488 | Open vSwitch CT limit 释放后使用漏洞 | |
| CVE-2026-89489 | OpenRISC 内核 or1k_atomic 任意内存访问漏洞 | |
| CVE-2026-89500 | ring-buffer 缓冲区读取页修复 | |
| CVE-2026-89497 | Orangefs 调试掩码解析空格处理缺陷 | |
| CVE-2026-89498 | Orangefs 双重释放漏洞 | |
| CVE-2026-89499 | ring-buffer 页面交换失败时停止远程读取 | |
| CVE-2026-89496 | ocfs2文件系统COW完成处理缺陷 | |
| CVE-2026-89501 | ring-buffer 子缓冲区调整时未持锁漏洞 |
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IV. Related Vulnerabilities
V. Comments for CVE-2026-89768
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