CVE-2026-89996— Linux dma-heap fd提前发布缺陷
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，已解决以下漏洞： dma-buf: dma-heap: 在 copy_to_user() 成功之前不要发布 fd 会分配一个 dma-buf，并在 将结果复制回用户空间之前，通过 -> 将 fd 安装到调用者的 fd 表中。如果最后的 失败，用户空间无法得知该 fd 的编号，但该 fd（及其底层的 dma-buf 引用）已经对同一进程内的其他线程可见，并会在整个进程生命周期内发生泄漏。 显而易见的“在失败路径上关闭它”的修复方式并不安全：一旦 执行完毕，另一个线程可能已经对该 fd 执行了
可能的 ATT&CK 技术 1 AI
T1562.008影响版本矩阵 10
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | c02a81fba74fe3488ad6b08bfb5a1329005418f8< 1bf6083a41f810d760c4dcd1b80c5194a92575aa |
affected |
c02a81fba74fe3488ad6b08bfb5a1329005418f8< 69d57dbadb27ffd5eef34fd184bab145500cdabc |
affected | ||
c02a81fba74fe3488ad6b08bfb5a1329005418f8< 0d4a5d218055db29b50cc07d3d73d27007c2a391 |
affected | ||
c02a81fba74fe3488ad6b08bfb5a1329005418f8< 30d0aff2c65a277135cfd8ea28fa1ee75e0ea4e0 |
affected | ||
5.6 |
affected | ||
< 5.6 |
unaffected | ||
6.12.112≤ 6.12.* |
unaffected | ||
6.18.52≤ 6.18.* |
unaffected | ||
| … +2 条更多 | |||
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一、 漏洞 CVE-2026-89996 基础信息
漏洞信息
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Vulnerability Title
dma-buf: dma-heap: don't publish fd before copy_to_user() succeeds
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
dma-buf: dma-heap: don't publish fd before copy_to_user() succeeds
DMA_HEAP_IOCTL_ALLOC allocates a dma-buf and installs an fd into the
caller's fd table via dma_buf_fd() -> fd_install() before
dma_heap_ioctl() copies the result back to userspace. If the trailing
copy_to_user() fails, userspace never learns the fd number, but the
fd (and the underlying dma-buf reference) are already visible to
other threads in the same process and are leaked for the lifetime of
the process.
The obvious "close it on the failure path" fix is unsafe: once
fd_install() has run, another thread can already dup() the fd, send
it via SCM_RIGHTS, or close() it and let its number be reused, so a
subsequent close_fd() from the ioctl path can operate on an unrelated
file. This was pointed out by Christian König on v1 [1].
Restructure the allocation path so that fd_install() is the last,
unfailable step of a successful ioctl:
1. heap->ops->allocate() creates the dma_buf.
2. get_unused_fd_flags() reserves an fd number in the caller's
fd table without publishing it, so
no other thread can observe it.
3. copy_to_user() delivers the fd number to userspace;
on failure the fd is returned with
put_unused_fd() and the dma_buf
reference is dropped with
dma_buf_put(), leaving no user-
visible state behind.
4. dma_buf_fd_install() publishes the fd and emits the
trace_dma_buf_fd tracepoint -- from
here on the ioctl cannot fail.
A new dma_buf_fd_install() helper is introduced in dma-buf.c to wrap
fd_install() together with the DMA_BUF_TRACE() call, preserving the
export tracing that dma_buf_fd() provides. dma_heap_ioctl_allocate()
is refactored to return the struct dma_buf * directly (returning
ERR_PTR on failure) so the caller holds the dmabuf reference across
steps 3 and 4.
The failure at step 3 is easily reachable from userspace: pass a
struct dma_heap_allocation_data that lives in a page whose protection
is flipped to PROT_READ between copy_from_user() and copy_to_user()
(e.g. via mprotect()). Before this change each such ioctl leaks one
dmabuf fd; after it, the fd table is unchanged on failure and only
/dev/dma_heap/<name> remains open.
No UAPI or heap-driver interface change.
[1] https://lore.kernel.org/dri-devel/175e98de-f414-47d7-81c1-c0fe0a8f7f62@amd.com/
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-2026-89996 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2026-89996 补丁与修复 (1)
CVE-2026-89996 其他参考 (3)
同批安全公告 · Linux · 2026-09-16 · 共 276 条
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| CVE-2026-90012 | 9.8 CRITICAL | SPI DMA映射所有权修复 |
| CVE-2026-89970 | 9.8 CRITICAL | NVM Target SQ拆除时超时工作未同步 |
| CVE-2026-89857 | 9.8 CRITICAL | QLogic qla2xxx NVMe LS拒绝竞态条件漏洞 |
| CVE-2026-89969 | 9.8 CRITICAL | Linux内核 nvmet-tcp 越界写入漏洞 |
| CVE-2026-89847 | 9.8 CRITICAL | qla2xxx SCSI驱动异步IOCB超时双重完成漏洞 |
| CVE-2026-89972 | 9.8 CRITICAL | NVMe驱动错误路径SRCU宽限期缺失漏洞 |
| CVE-2026-89990 | 9.8 CRITICAL | Ceph ceph_mds_check_access 互斥锁缺失漏洞 |
| CVE-2026-90036 | 9.8 CRITICAL | Linux NFSd 阻塞锁收割时释放后使用漏洞 |
| CVE-2026-90038 | 9.8 CRITICAL | Linux内核NFSD导出撤销后使用漏洞 |
| CVE-2026-90037 | 9.8 CRITICAL | Linux内核NFSD close_lru释放后使用漏洞 |
| CVE-2026-89788 | 9.8 CRITICAL | Linux kernel ksmbd 释放后使用漏洞 |
| CVE-2026-89783 | 9.8 CRITICAL | Linux内核 xfrm6 越界写入漏洞 |
| CVE-2026-90042 | 9.8 CRITICAL | Ceph 虚拟内存分配缓冲区文件名解密漏洞 |
| CVE-2026-89778 | 9.8 CRITICAL | isofs 空 zisofs 块页面数组越界访问漏洞 |
| CVE-2026-89915 | 9.3 CRITICAL | KVM arm64 移除虚拟机级 VNCR 映射计数器 |
| CVE-2026-90049 | 9.3 CRITICAL | 内核网络子系统中skb_zerocopy处理中的缺陷 |
| CVE-2026-89775 | 9.3 CRITICAL | KVM arm64 VNCR TLB大小计算漏洞 |
| CVE-2026-89916 | 9.3 CRITICAL | KVM arm64 VNCR失效重试漏洞 |
| CVE-2026-89930 | 9.3 CRITICAL | KVM嵌套虚拟化本地TLB刷新漏洞 |
显示前 20 条，共 276 条。 查看全部 → →
IV. Related Vulnerabilities
V. Comments for CVE-2026-89996
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