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CVE-2025-68214— timers: Fix NULL function pointer race in timer_shutdown_sync()

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timer_shutdown_sync与定时器到期存在竞争条件，可能导致WARN_ON触发。

AI Predicted 5.3 Difficulty: Moderate EPSS 0.13% · P2

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 14

VendorProduct Version RangeStatus
Linux Linux debbcf812d735003c96c5e5968a3cfa4e1fbd1af< ba43ac025c4318241f8edf94f31d2eebab86991b affected
334c33aa487be406a149c8b87c38c8399d2dba8d< 1a975716cc8977f461e45e28e3e5977d46ad7a6a affected
0cc04e80458a822300b93f82ed861a513edde194< 6665fbd7730b26d770c232b20d1b907e6a67a914 affected
0cc04e80458a822300b93f82ed861a513edde194< 176725f4848376530a0f0da9023f956afcc33585 affected
0cc04e80458a822300b93f82ed861a513edde194< a01efa7a780c42ac5170a949bd95c9786ffcc60a affected
0cc04e80458a822300b93f82ed861a513edde194< 20739af07383e6eb1ec59dcd70b72ebfa9ac362c affected
6.1.158< 6.1.159 affected
6.2 affected
… +6 more rows
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I. Basic Information for CVE-2025-68214

Vulnerability Information
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Vulnerability Title
timers: Fix NULL function pointer race in timer_shutdown_sync()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: timers: Fix NULL function pointer race in timer_shutdown_sync() There is a race condition between timer_shutdown_sync() and timer expiration that can lead to hitting a WARN_ON in expire_timers(). The issue occurs when timer_shutdown_sync() clears the timer function to NULL while the timer is still running on another CPU. The race scenario looks like this: CPU0 CPU1 <SOFTIRQ> lock_timer_base() expire_timers() base->running_timer = timer; unlock_timer_base() [call_timer_fn enter] mod_timer() ... timer_shutdown_sync() lock_timer_base() // For now, will not detach the timer but only clear its function to NULL if (base->running_timer != timer) ret = detach_if_pending(timer, base, true); if (shutdown) timer->function = NULL; unlock_timer_base() [call_timer_fn exit] lock_timer_base() base->running_timer = NULL; unlock_timer_base() ... // Now timer is pending while its function set to NULL. // next timer trigger <SOFTIRQ> expire_timers() WARN_ON_ONCE(!fn) // hit ... lock_timer_base() // Now timer will detach if (base->running_timer != timer) ret = detach_if_pending(timer, base, true); if (shutdown) timer->function = NULL; unlock_timer_base() The problem is that timer_shutdown_sync() clears the timer function regardless of whether the timer is currently running. This can leave a pending timer with a NULL function pointer, which triggers the WARN_ON_ONCE(!fn) check in expire_timers(). Fix this by only clearing the timer function when actually detaching the timer. If the timer is running, leave the function pointer intact, which is safe because the timer will be properly detached when it finishes running.
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timer_shutdown_sync与定时器到期存在竞争条件，可能导致WARN_ON触发。
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 debbcf812d735003c96c5e5968a3cfa4e1fbd1af ~ ba43ac025c4318241f8edf94f31d2eebab86991b -
Linux Linux 6.2 -

II. Public POCs for CVE-2025-68214

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III. Intelligence Information for CVE-2025-68214

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Other References for CVE-2025-68214 (5)

Same Patch Batch · Linux · 2025-12-16 · 156 CVEs total

CVE-2025-68284 9.8 CRITICAL libceph: prevent potential out-of-bounds writes in handle_auth_session_key()
CVE-2025-40350 9.8 CRITICAL net/mlx5e: RX, Fix generating skb from non-linear xdp_buff for striding RQ
CVE-2025-68263 9.8 CRITICAL ksmbd: ipc: fix use-after-free in ipc_msg_send_request
CVE-2025-68301 9.8 CRITICAL net: atlantic: fix fragment overflow handling in RX path
CVE-2025-68192 9.8 CRITICAL net: usb: qmi_wwan: initialize MAC header offset in qmimux_rx_fixup
CVE-2025-68285 9.8 CRITICAL libceph: fix potential use-after-free in have_mon_and_osd_map()
CVE-2025-68315 9.8 CRITICAL f2fs: fix to detect potential corrupted nid in free_nid_list
CVE-2025-68255 8.8 HIGH staging: rtl8723bs: fix stack buffer overflow in OnAssocReq IE parsing
CVE-2025-68256 8.8 HIGH staging: rtl8723bs: fix out-of-bounds read in rtw_get_ie() parser
CVE-2025-68226 8.8 HIGH smb: client: fix incomplete backport in cfids_invalidation_worker()
CVE-2025-68304 8.8 HIGH Bluetooth: hci_core: lookup hci_conn on RX path on protocol side
CVE-2025-68314 8.8 HIGH drm/msm: make sure last_fence is always updated
CVE-2025-40362 8.8 HIGH ceph: fix multifs mds auth caps issue
CVE-2025-68250 8.2 HIGH hung_task: fix warnings caused by unaligned lock pointers
CVE-2025-68183 7.8 HIGH ima: don't clear IMA_DIGSIG flag when setting or removing non-IMA xattr
CVE-2025-68294 7.8 HIGH io_uring/net: ensure vectored buffer node import is tied to notification
CVE-2025-68208 7.8 HIGH bpf: account for current allocated stack depth in widen_imprecise_scalars()
CVE-2025-68207 7.8 HIGH drm/xe/guc: Synchronize Dead CT worker with unbind
CVE-2025-68303 7.8 HIGH platform/x86: intel: punit_ipc: fix memory corruption
CVE-2025-68181 7.8 HIGH drm/radeon: Remove calls to drm_put_dev()

Showing top 20 of 156 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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