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Linux KernelOperating system · Linux

CVE-2025-37747

MEDIUM · 5.5 CVSS v3.1 Published 2025-05-01
Fix available
A fix is available. Upgrade to 5.16 / 6.2 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: perf: Fix hang while freeing sigtrap event Perf can hang while freeing a sigtrap event if a related deferred signal hadn't managed to be sent before the file got closed: perf_event_overflow() task_work_add(perf_pending_task) fput() task_work_add(____fput()) task_work_run() ____fput() perf_release() perf_event_release_kernel() _free_event() perf_pending_task_sync() task_work_cancel() -> FAILED rcuwait_wait_event() Once task_work_run() is running, the list of pending callbacks is removed from the task_struct and from this point on task_work_cancel() can't remove any pending and not yet started work items, hence the task_work_cancel() failure and the hang on rcuwait_wait_event(). Task work could be changed to remove one work at a time, so a work running on the current task can always cancel a pending one, however the wait / wake design is still subject to inverted dependencies when remote targets are involved, as pictured by Oleg: T1 T2 fd = perf_event_open(pid => T2->pid); fd = perf_event_open(pid => T1->pid); close(fd) close(fd) <IRQ> <IRQ> perf_event_overflow() perf_event_overflow() task_work_add(perf_pending_task) task_work_add(perf_pending_task) </IRQ> </IRQ> fput() fput() task_work_add(____fput()) task_work_add(____fput()) task_work_run() task_work_run() ____fput() ____fput() perf_release() perf_release() perf_event_release_kernel() perf_event_release_kernel() _free_event() _free_event() perf_pending_task_sync() perf_pending_task_sync() rcuwait_wait_event() rcuwait_wait_event() Therefore the only option left is to acquire the event reference count upon queueing the perf task work and release it from the task work, just like it was done before 3a5465418f5f ("perf: Fix event leak upon exec and file release") but without the leaks it fixed. Some adjustments are necessary to make it work: * A child event might dereference its parent upon freeing. Care must be taken to release the parent last. * Some places assuming the event doesn't have any reference held and therefore can be freed right away must instead put the reference and let the reference counting to its job.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.15.165, < 5.16>= 6.1.103, < 6.2>= 6.6.44, < 6.7>= 6.10.3, < 6.12.24>= 6.13, < 6.13.12>= 6.14, < 6.14.3= 6.15

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.16 / 6.2 / 6.7 or later
Fixed in 5.166.26.7
Vendor patch git.kernel.org →
Recommended fix High confidence

Kernel 5.16+ (for 5.15.x), 6.2+ (for 6.1.x), 6.7+ (for 6.6.x), or 6.12.24+ (for 6.10.x/6.12.x)

  1. Identify the current running kernel version using `uname -r`
  2. Check if the current version falls within any of the affected ranges: 5.15.165 to 5.15.x (where x < 16), 6.1.103 to 6.1.x (where x < 2), 6.6.44 to 6.6.x (where x < 7), or 6.10.3 to 6.12.x (where x < 24)
  3. If affected, upgrade to a kernel version that includes the fix: 5.16 or later for 5.15.x users, 6.2 or later for 6.1.x users, 6.7 or later for 6.6.x users, or 6.12.24 or later for 6.10.x/6.12.x users
  4. For enterprise distributions, apply the vendor-provided kernel security update that backports the fix commit 1267bd38f161c1a27d9b722de017027167a225a0
  5. Reboot the system to load the fixed kernel
  6. Verify the fix by checking the kernel version and confirming no perf event hangs occur during normal operation
Caveat Kernel upgrades may require system reboot and could introduce compatibility issues with custom kernel modules or specific hardware drivers; ensure backup and test compatibility in non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

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