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CVE-2025-21908— NFS: fix nfs_release_folio() to not deadlock via kcompactd writeback

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nfs_release_folio在kcompactd上下文中可能死锁。

AI Predicted 5.5 Difficulty: Theoretical EPSS 0.15% · P4

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 96780ca55e3cbf4f150fd5a833a61492c9947b5b< ab0727d6e2196682351c25c1dd112136f6991f11 affected
96780ca55e3cbf4f150fd5a833a61492c9947b5b< 5ae31c54cff745832b9bd5b32e71f3d1b607cd1e affected
96780ca55e3cbf4f150fd5a833a61492c9947b5b< 8253ff29edcb429a9a6c75710941c6a16a9a34b1 affected
96780ca55e3cbf4f150fd5a833a61492c9947b5b< ce6d9c1c2b5cc785016faa11b48b6cd317eb367e affected
6.3 affected
< 6.3 unaffected
6.6.83≤ 6.6.* unaffected
6.12.19≤ 6.12.* unaffected
… +2 more rows
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I. Basic Information for CVE-2025-21908

Vulnerability Information
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Vulnerability Title
NFS: fix nfs_release_folio() to not deadlock via kcompactd writeback
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: NFS: fix nfs_release_folio() to not deadlock via kcompactd writeback Add PF_KCOMPACTD flag and current_is_kcompactd() helper to check for it so nfs_release_folio() can skip calling nfs_wb_folio() from kcompactd. Otherwise NFS can deadlock waiting for kcompactd enduced writeback which recurses back to NFS (which triggers writeback to NFSD via NFS loopback mount on the same host, NFSD blocks waiting for XFS's call to __filemap_get_folio): 6070.550357] INFO: task kcompactd0:58 blocked for more than 4435 seconds. {--- [58] "kcompactd0" [<0>] folio_wait_bit+0xe8/0x200 [<0>] folio_wait_writeback+0x2b/0x80 [<0>] nfs_wb_folio+0x80/0x1b0 [nfs] [<0>] nfs_release_folio+0x68/0x130 [nfs] [<0>] split_huge_page_to_list_to_order+0x362/0x840 [<0>] migrate_pages_batch+0x43d/0xb90 [<0>] migrate_pages_sync+0x9a/0x240 [<0>] migrate_pages+0x93c/0x9f0 [<0>] compact_zone+0x8e2/0x1030 [<0>] compact_node+0xdb/0x120 [<0>] kcompactd+0x121/0x2e0 [<0>] kthread+0xcf/0x100 [<0>] ret_from_fork+0x31/0x40 [<0>] ret_from_fork_asm+0x1a/0x30 ---} [akpm@linux-foundation.org: fix build]
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nfs_release_folio在kcompactd上下文中可能死锁。
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 96780ca55e3cbf4f150fd5a833a61492c9947b5b ~ ab0727d6e2196682351c25c1dd112136f6991f11 -
Linux Linux 6.3 -

II. Public POCs for CVE-2025-21908

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III. Intelligence Information for CVE-2025-21908

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Patches & Fixes for CVE-2025-21908 (1)

Same Patch Batch · Linux · 2025-04-01 · 93 CVEs total

CVE-2025-21927 9.8 CRITICAL nvme-tcp: fix potential memory corruption in nvme_tcp_recv_pdu()
CVE-2025-21954 9.8 CRITICAL netmem: prevent TX of unreadable skbs
CVE-2025-21969 8.8 HIGH Bluetooth: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd
CVE-2025-21955 8.8 HIGH ksmbd: prevent connection release during oplock break notification
CVE-2025-21972 8.8 HIGH net: mctp: unshare packets when reassembling
CVE-2025-21946 8.8 HIGH ksmbd: fix out-of-bounds in parse_sec_desc()
CVE-2025-21945 8.8 HIGH ksmbd: fix use-after-free in smb2_lock
CVE-2025-21967 8.8 HIGH ksmbd: fix use-after-free in ksmbd_free_work_struct
CVE-2025-21947 8.1 HIGH ksmbd: fix type confusion via race condition when using ipc_msg_send_request
CVE-2025-21923 7.8 HIGH HID: hid-steam: Fix use-after-free when detaching device
CVE-2025-21934 7.8 HIGH rapidio: fix an API misues when rio_add_net() fails
CVE-2025-21949 7.8 HIGH LoongArch: Set hugetlb mmap base address aligned with pmd size
CVE-2025-21939 7.8 HIGH drm/xe/hmm: Don't dereference struct page pointers without notifier lock
CVE-2025-21914 7.8 HIGH slimbus: messaging: Free transaction ID in delayed interrupt scenario
CVE-2025-21924 7.8 HIGH net: hns3: make sure ptp clock is unregister and freed if hclge_ptp_get_cycle returns an e
CVE-2025-21958 7.8 HIGH Revert "openvswitch: switch to per-action label counting in conntrack"
CVE-2025-21965 7.8 HIGH sched_ext: Validate prev_cpu in scx_bpf_select_cpu_dfl()
CVE-2025-21926 7.8 HIGH net: gso: fix ownership in __udp_gso_segment
CVE-2025-21919 7.8 HIGH sched/fair: Fix potential memory corruption in child_cfs_rq_on_list
CVE-2025-21985 7.8 HIGH drm/amd/display: Fix out-of-bound accesses

Showing top 20 of 93 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-21908

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