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CVE-2025-21643— netfs: Fix kernel async DIO

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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netfs_unbuffered_write_iter_locked函数错误地将内核异步DIO写入处理为用户空间写入。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.21% · P11

Possible ATT&CK Techniques 1 AI

T1499.001 · OS Exhaustion Flood

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 153a9961b551101cd38e94e26cd92fbfd198b19b< 9f3a265836844eda30bf34c2584b8011fd4f0f49 affected
153a9961b551101cd38e94e26cd92fbfd198b19b< 3f6bc9e3ab9b127171d39f9ac6eca1abb693b731 affected
6.8 affected
< 6.8 unaffected
6.12.10≤ 6.12.* unaffected
6.13≤ * unaffected
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I. Basic Information for CVE-2025-21643

Vulnerability Information
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Vulnerability Title
netfs: Fix kernel async DIO
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix kernel async DIO Netfslib needs to be able to handle kernel-initiated asynchronous DIO that is supplied with a bio_vec[] array. Currently, because of the async flag, this gets passed to netfs_extract_user_iter() which throws a warning and fails because it only handles IOVEC and UBUF iterators. This can be triggered through a combination of cifs and a loopback blockdev with something like: mount //my/cifs/share /foo dd if=/dev/zero of=/foo/m0 bs=4K count=1K losetup --sector-size 4096 --direct-io=on /dev/loop2046 /foo/m0 echo hello >/dev/loop2046 This causes the following to appear in syslog: WARNING: CPU: 2 PID: 109 at fs/netfs/iterator.c:50 netfs_extract_user_iter+0x170/0x250 [netfs] and the write to fail. Fix this by removing the check in netfs_unbuffered_write_iter_locked() that causes async kernel DIO writes to be handled as userspace writes. Note that this change relies on the kernel caller maintaining the existence of the bio_vec array (or kvec[] or folio_queue) until the op is complete.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
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netfs_unbuffered_write_iter_locked函数错误地将内核异步DIO写入处理为用户空间写入。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 153a9961b551101cd38e94e26cd92fbfd198b19b ~ 9f3a265836844eda30bf34c2584b8011fd4f0f49 -
Linux Linux 6.8 -

II. Public POCs for CVE-2025-21643

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III. Intelligence Information for CVE-2025-21643

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Patches & Fixes for CVE-2025-21643 (2)

Same Patch Batch · Linux · 2025-01-19 · 47 CVEs total

CVE-2024-57929 7.8 HIGH dm array: fix releasing a faulty array block twice in dm_array_cursor_end
CVE-2025-21631 7.8 HIGH block, bfq: fix waker_bfqq UAF after bfq_split_bfqq()
CVE-2025-21652 7.8 HIGH ipvlan: Fix use-after-free in ipvlan_get_iflink().
CVE-2024-57918 7.8 HIGH drm/amd/display: fix page fault due to max surface definition mismatch
CVE-2024-57926 7.8 HIGH drm/mediatek: Set private->all_drm_private[i]->drm to NULL if mtk_drm_bind returns err
CVE-2024-57921 7.8 HIGH drm/amdgpu: Add a lock when accessing the buddy trim function
CVE-2025-21646 7.5 HIGH afs: Fix the maximum cell name length
CVE-2025-21647 7.3 HIGH sched: sch_cake: add bounds checks to host bulk flow fairness counts
CVE-2025-21640 7.1 HIGH sctp: sysctl: cookie_hmac_alg: avoid using current->nsproxy
CVE-2025-21638 7.1 HIGH sctp: sysctl: auth_enable: avoid using current->nsproxy
CVE-2025-21650 7.1 HIGH net: hns3: fixed hclge_fetch_pf_reg accesses bar space out of bounds issue
CVE-2025-21637 7.1 HIGH sctp: sysctl: udp_port: avoid using current->nsproxy
CVE-2024-57912 iio: pressure: zpa2326: fix information leak in triggered buffer
CVE-2024-57910 iio: light: vcnl4035: fix information leak in triggered buffer
CVE-2024-57925 ksmbd: fix a missing return value check bug
CVE-2024-57911 iio: dummy: iio_simply_dummy_buffer: fix information leak in triggered buffer
CVE-2024-57913 usb: gadget: f_fs: Remove WARN_ON in functionfs_bind
CVE-2024-57914 usb: typec: tcpci: fix NULL pointer issue on shared irq case
CVE-2024-57928 netfs: Fix enomem handling in buffered reads
CVE-2024-57927 nfs: Fix oops in nfs_netfs_init_request() when copying to cache

Showing top 20 of 47 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-21643

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