CVE-2026-89791— Linux perf 工具竞态导致 UAF 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。
In the Linux kernel, the following vulnerability has been resolved: perf: Fix use-after-free when perf mmap() revival races with the last munmap() perf_mmap_close() drops rb->mmap_count without holding event->mmap_mutex (the refcount_dec_and_test() right befor
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一、 漏洞 CVE-2026-89791 基础信息
漏洞信息
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Vulnerability Title
perf: Fix use-after-free when perf mmap() revival races with the last munmap()
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
perf: Fix use-after-free when perf mmap() revival races with the last munmap()
perf_mmap_close() drops rb->mmap_count *without* holding
event->mmap_mutex (the refcount_dec_and_test() right before the
refcount_dec_and_mutex_lock() of event->mmap_count). A concurrent
perf_mmap_rb() can slot its entire "revival" path into that window
(perf_mmap holds event->mmap_mutex for its whole duration, including
rb_alloc):
munmap side (perf_mmap_close) mmap side (perf_mmap_rb)
----------------------------------- --------------------------------
rb->mmap_count 1 -> 0 (no lock) (holds event->mmap_mutex)
inc_not_zero(rb->mmap_count) fails
ring_buffer_attach(event, NULL)
rb_alloc() + attach new rb
refcount_set(&event->mmap_count, 1)
lock; event->mmap_count 1 -> 0
ring_buffer_attach(event, NULL)
ring_buffer_put() -> frees the *new* rb
The revival's refcount_set(&event->mmap_count, 1) is an invisible
1 -> 1 write: the close frees the just-revived buffer although the
other process still has it mapped -- a page-level use-after-free
allowing local privilege escalation to root by any unprivileged user
(default kernel.perf_event_paranoid=2).
Swap the order of the two counter updates: event->mmap_count is
dropped first via refcount_dec_and_mutex_lock(), so its 1 -> 0
transition and the ring_buffer_attach() stay serialized with
perf_mmap(). rb->mmap_count == 0 then implies every event using the
buffer is detached already, so the result of the rb->mmap_count drop
can gate the remaining teardown directly and detach_rest is no longer
needed.
An earlier fix for this race from Kyle Zeng and David Lee takes
event->mmap_mutex around both counter updates [0]; here the not-last
close stays lockless.
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-2026-89791 的公开POC
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CVE-2026-89791 其他参考 (3)
同批安全公告 · Linux · 2026-09-16 · 共 20 条
| CVE-2026-89784 | SunRPC rpcb_register_inet4/6 返回值检查漏洞 | |
| CVE-2026-89774 | Linux内核蓝牙SCO连接准备函数缺陷 | |
| CVE-2026-89775 | KVM arm64 VNCR TLB大小计算漏洞 | |
| CVE-2026-89776 | vxlan: vnifilter 属性长度校验缺陷 | |
| CVE-2026-89778 | isofs 空 zisofs 块页面数组越界访问漏洞 | |
| CVE-2026-89777 | vfio/pci初始化失败时未清空msi_perm内存泄漏 | |
| CVE-2026-89779 | NTFS3文件系统efs size验证缺陷 | |
| CVE-2026-89781 | Linux NTFS3 驱动越界读取漏洞 | |
| CVE-2026-89780 | Qualcomm rmnet 去聚合帧 skb->dev 恢复漏洞 | |
| CVE-2026-89782 | NTFS3 fs/ntfs3 拒绝重启表增长漏洞 | |
| CVE-2026-89793 | ublk 只读设备 mmap 权限清除漏洞 | |
| CVE-2026-89783 | Linux内核 xfrm6 越界写入漏洞 | |
| CVE-2026-89785 | Linux内核ntfs3驱动越界读取漏洞 | |
| CVE-2026-89787 | Ext4 文件系统 ext4_search_dir 缓冲区溢出漏洞 | |
| CVE-2026-89786 | Linux内核ext4文件系统越界读取漏洞 | |
| CVE-2026-89788 | Linux kernel ksmbd 释放后使用漏洞 | |
| CVE-2026-89790 | Linux内核ipv6模块除零漏洞 | |
| CVE-2026-89789 | Linux内核GTP驱动UAF漏洞 | |
| CVE-2026-89792 | Linux ksmbd 共享配置越界读取漏洞 |
IV. Related Vulnerabilities
V. Comments for CVE-2026-89791
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