CVE-2026-97945— x86/mm：修复MADV_FREE与THP导致的用户空间数据丢失
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。
在 Linux 内核中，已修复以下漏洞： x86/mm：修复 MADV_FREE 与 THP（大页面）导致的用户空间数据丢失问题 一些使用 Polars（一个数据分析库）的用户因该漏洞在生产环境中丢失了数据。该问题的触发条件似乎是恰好同时具备大页面、MADV_FREE 标志以及较重的页面回收压力。 函数在修改页面目录条目（PMD）时，会使用 掩码对旧值进行屏蔽，从而静默地丢弃了硬件脏位（dirty bit）。随后调用的 本应在写保护时将 转换为 ，但由于脏位已被提前剥离，没有数据可供转换。 相比之下， 在掩码中保留
可能的 ATT&CK 技术 1 AI
T1564.004 · NTFS File Attributes影响版本矩阵 12
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | bb3aadf7d446aaf22c725b274e2c194ac5cb2111< b5dec6dfb593d81fec15ba43c4fe5d58f10a49a2 |
affected |
bb3aadf7d446aaf22c725b274e2c194ac5cb2111< e4d569fe2f436a9b58c048fefabf56eab68c1b7e |
affected | ||
bb3aadf7d446aaf22c725b274e2c194ac5cb2111< 55ddbc2ca6d5db64d44c3fb8f8705b4d39eb30b7 |
affected | ||
bb3aadf7d446aaf22c725b274e2c194ac5cb2111< a5ad97cbcfcec31430268441c10eedde73200177 |
affected | ||
bb3aadf7d446aaf22c725b274e2c194ac5cb2111< f7491d7c81db0e7c304a7bd757a76d2fbeaff80e |
affected | ||
6.6 |
affected | ||
< 6.6 |
unaffected | ||
6.6.158≤ 6.6.* |
unaffected | ||
| … +4 条更多 | |||
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一、 漏洞 CVE-2026-97945 基础信息
漏洞信息
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Vulnerability Title
x86/mm: Fix user-space data loss with MADV_FREE and THP
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
x86/mm: Fix user-space data loss with MADV_FREE and THP
Some of users of Polars (a data analytics library) have lost production
data from this bug. They seem to have just the right combination of
huge pages, MADV_FREE and heavy reclaim pressure.
pmd_modify() masks the old value with (_HPAGE_CHG_MASK & ~_PAGE_DIRTY),
silently discarding the hardware dirty bit. The subsequent
pmd_mksaveddirty() call is supposed to transfer _PAGE_DIRTY into
_PAGE_SAVED_DIRTY when write-protecting, but the dirty bit was already
stripped from the value, so there is nothing left to transfer.
Contrast with pte_modify(), which keeps _PAGE_DIRTY_BITS in its mask,
and pud_modify(), which keeps _HPAGE_CHG_MASK untouched: pmd_modify()
is the odd one out. Any pmd_modify() on a writable, dirty PMD loses
the dirty state.
One visible consequence is data loss with MADV_FREE on PMD-mapped THP:
memset(buf, 0x5A, size); // PMD-mapped THP, PMD dirty
madvise(buf, size, MADV_FREE); // PMD cleaned but left writable,
// folio marked lazyfree
memset(buf, 0x5A, size); // hardware sets _PAGE_DIRTY again
mprotect(buf, size, PROT_READ); // pmd_modify() drops the dirty bit
mprotect(buf, size, PROT_READ|PROT_WRITE);
// ... memory pressure ...
Reclaim (e.g. under memcg pressure) then finds the lazyfree folio with
no dirty bit set anywhere and frees it in
__discard_anon_folio_pmd_locked(), even though the data was rewritten
after MADV_FREE; subsequent reads fault in fresh zero pages. NUMA
hinting alone can trigger the same loss, as do_huge_pmd_numa_page()
restores the PMD through pmd_modify() as well.
PMD-mapped file THPs are affected too: mprotect()/NUMA hinting dropping
the dirty bit means rewritten data is never written back.
Fix it by keeping _PAGE_DIRTY in the preserved mask, exactly like
pte_modify() and pud_modify() do. The existing
pmd_mksaveddirty()/pmd_clear_saveddirty() pair then performs the
hardware-dirty <-> saved-dirty transition based on the write bit,
preserving the shadow-stack encoding rules.
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-2026-97945 的公开POC
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|---|
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CVE-2026-97945 补丁与修复 (4)
CVE-2026-97945 其他参考 (1)
同批安全公告 · Linux · 2026-09-25 · 共 372 条
| CVE-2026-100075 | 9.8 CRITICAL | RDMA/srpt：srpt_alloc_rw_ctxs() 未释放计数器修复 |
| CVE-2026-97555 | 8.8 HIGH | smb客户端：修复DACL所有者/组重写中的堆溢出漏洞 |
| CVE-2026-97957 | 8.8 HIGH | hinic 邮箱段缓冲区溢出漏洞 |
| CVE-2026-97527 | 8.8 HIGH | qla2xxx SCSI驱动程序 NVMe未解决上下文列表竞争条件漏洞 |
| CVE-2026-97528 | 8.8 HIGH | QLogic qla2xxx驱动LS拒绝错误NVMe内存泄漏漏洞 |
| CVE-2026-98115 | 8.8 HIGH | ksmbd 注销期间会话安全排空漏洞 |
| CVE-2026-97525 | 8.2 HIGH | x86/mm/pat：内核页表分裂页表分配漏洞 |
| CVE-2026-98069 | 8.1 HIGH | Net/RDS rds_conn_shutdown() 快速路径锁获取漏洞 |
| CVE-2026-97573 | 8.1 HIGH | bnxt_en 驱动 bnxt_rx_ring_reset 缓冲区分配失败漏洞 |
| CVE-2026-97570 | 8.1 HIGH | bnxt_en: 修复因SW TPA ID绑定问题导致的崩溃漏洞 |
| CVE-2026-98130 | 8.1 HIGH | SCTP定时器启动竞争条件漏洞 |
| CVE-2026-98070 | 8.1 HIGH | Linux RDS 模块远程代码执行漏洞 |
| CVE-2026-97941 | 7.8 HIGH | Linux 内核 slab 内存分配器竞态条件漏洞 |
| CVE-2026-97575 | 7.8 HIGH | v4l2-ctrls AV1瓦片计数验证漏洞 |
| CVE-2026-97576 | 7.8 HIGH | V4L2-ctrls HEVC 瓦片计数验证漏洞 |
| CVE-2026-98112 | 7.8 HIGH | ksmbd 网络接口事件中监听器任务生命周期修复漏洞 |
| CVE-2026-98002 | 7.8 HIGH | AMD IOMMU 嵌套域分配中错误检查失效漏洞 |
| CVE-2026-97937 | 7.8 HIGH | Linux内核ftrace远程代码执行漏洞 |
| CVE-2026-97580 | 7.8 HIGH | rkvdec HEVC解析数组越界漏洞 |
| CVE-2026-97940 | 7.8 HIGH | IPv6 修复 fib6 遍历器在 seq 停止时存在 UAF 漏洞 |
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IV. Related Vulnerabilities
V. Comments for CVE-2026-97945
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