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High · 7.8 CVE-2025-21655 EUVD-2025-2604GHSA-vwm2-fvjj-vcv3

io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period

Published Jan 20, 2025 · Updated Nov 10, 2026 · Assigned by Linux

Vendor: Linux Product: Linux Package: linux Package: linux Package: linux-allwinner-5.19 Package: linux-aws Package: linux-aws-5.0 Package: linux-aws-5.11 Package: linux-aws-5.13 Package: linux-aws-5.19 Package: linux-aws-5.3 Package: linux-aws-5.8 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-aws-6.8 Package: linux-azure Package: linux-azure-5.11 Package: linux-azure-5.13 Package: linux-azure-5.19 Package: linux-azure-5.3 Package: linux-azure-5.8 Package: linux-azure-6.11 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-6.8 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.2 Package: linux-azure-nvidia Package: linux-fips Package: linux-gcp Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.19 Package: linux-gcp-5.3 Package: linux-gcp-5.8 Package: linux-gcp-6.11 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gcp-6.8 Package: linux-gke Package: linux-gke-4.15 Package: linux-gke-5.15 Package: linux-gke-5.4 Package: linux-gkeop Package: linux-gkeop-5.15 Package: linux-gkeop-5.4 Package: linux-hwe Package: linux-hwe-5.11 Package: linux-hwe-5.13 Package: linux-hwe-5.19 Package: linux-hwe-5.8 Package: linux-hwe-6.11 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-6.8 Package: linux-hwe-edge Package: linux-ibm Package: linux-ibm-6.8 Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-lowlatency Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.2 Package: linux-lowlatency-hwe-6.5 Package: linux-lowlatency-hwe-6.8 Package: linux-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-6.8 Package: linux-nvidia-lowlatency Package: linux-nvidia-tegra Package: linux-oem Package: linux-oem-5.10 Package: linux-oem-5.13 Package: linux-oem-5.14 Package: linux-oem-5.17 Package: linux-oem-5.6 Package: linux-oem-6.0 Package: linux-oem-6.1 Package: linux-oem-6.11 Package: linux-oem-6.5 Package: linux-oem-6.8 Package: linux-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.3 Package: linux-oracle-5.8 Package: linux-oracle-6.5 Package: linux-oracle-6.8 Package: linux-raspi Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-realtime-6.8 Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-riscv-6.5 Package: linux-riscv-6.8 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Package: linux-xilinx Platform: Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

In the Linux kernel, the following vulnerability has been resolved:

io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period

io_eventfd_do_signal() is invoked from an RCU callback, but when
dropping the reference to the io_ev_fd, it calls io_eventfd_free()
directly if the refcount drops to zero. This isn't correct, as any
potential freeing of the io_ev_fd should be deferred another RCU grace
period.

Just call io_eventfd_put() rather than open-code the dec-and-test and
free, which will correctly defer it another RCU grace period.

Affected products

VendorProductAffectedFixed
Linux Linux 6.1 6.1.125

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 linux 6.12.10-1 —
Debian 13 linux 6.12.10-1 —
Debian 12 linux 6.1.128-1 DSA-5860-1
Debian 11 linux-6.1 6.1.128-1~deb11u1 DLA-4076-1
ReleasePackageFixed inAdvisory
Ubuntu 24.04 LTS linux 6.8.0-60.63 USN-7513-1
Ubuntu 24.04 LTS linux-aws 6.8.0-1029.31 USN-7513-1
Ubuntu 24.04 LTS linux-azure 6.8.0-1029.34 USN-7513-3
Ubuntu 24.04 LTS linux-azure-6.11 6.11.0-1012.12~24.04.1 —
Ubuntu 24.04 LTS linux-azure-nvidia 6.8.0-1016.17 USN-7522-1
Ubuntu 24.04 LTS linux-gcp 6.8.0-1030.32 USN-7515-2
Ubuntu 24.04 LTS linux-gcp-6.11 6.11.0-1011.11~24.04.1 —
Ubuntu 24.04 LTS linux-gke 6.8.0-1025.29 USN-7515-1
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1012.14 USN-7515-2
Ubuntu 24.04 LTS linux-hwe-6.11 6.11.0-21.21~24.04.1 USN-7379-1
Ubuntu 24.04 LTS linux-ibm 6.8.0-1026.26 USN-7513-1
Ubuntu 24.04 LTS linux-lowlatency-hwe-6.11 6.11.0-1011.12~24.04.1 USN-7381-1
Ubuntu 24.04 LTS linux-nvidia 6.8.0-1028.31 USN-7514-1
Ubuntu 24.04 LTS linux-nvidia-6.11 6.11.0-1007.7 —
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1028.31.1 USN-7514-1
Ubuntu 24.04 LTS linux-nvidia-tegra 6.8.0-1008.8 —
Ubuntu 24.04 LTS linux-oem-6.11 6.11.0-1017.17 USN-7382-1
Ubuntu 24.04 LTS linux-oem-6.8 6.8.0-1028.28 USN-7513-3
Ubuntu 24.04 LTS linux-oracle 6.8.0-1026.27 USN-7513-1
Ubuntu 24.04 LTS linux-raspi 6.8.0-1028.32 USN-7524-1
Ubuntu 24.04 LTS linux-realtime +1 No fix yet —
Ubuntu 24.04 LTS linux-riscv +1 6.8.0-60.63.1 USN-7513-1
Ubuntu 24.04 LTS linux-xilinx 6.8.0-1017.18 —
Ubuntu 22.04 LTS linux-aws-6.8 6.8.0-1029.31~22.04.1 USN-7513-1
Ubuntu 22.04 LTS linux-azure-6.8 6.8.0-1029.34~22.04.1 USN-7513-3
Ubuntu 22.04 LTS linux-gcp-6.8 6.8.0-1030.32~22.04.1 USN-7515-2
Ubuntu 22.04 LTS linux-hwe-6.8 6.8.0-60.63~22.04.1 USN-7513-4
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1026.26~22.04.1 —
Ubuntu 22.04 LTS linux-lowlatency-hwe-6.8 6.8.0-60.63.1~22.04.1 USN-7513-1
Ubuntu 22.04 LTS linux-nvidia-6.8 6.8.0-1028.31~22.04.1 USN-7514-1
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1026.27~22.04.1 USN-7513-5
Ubuntu 22.04 LTS linux-riscv +32 No fix yet —
Ubuntu 22.04 LTS linux-riscv-6.8 6.8.0-62.65~22.04.1 —
Ubuntu 20.04 LTS linux-gke +28 No fix yet —
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Show 3 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu Pro Realtime 24.04 LTS linux-raspi-realtime 6.8.0-2023.24 USN-7523-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1022.23 USN-7513-2
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1022.23~22.04.1 —
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-78.78+fips1 —
ReleasePackageFixed inAdvisory
RHEL 10 rv +76 6.12.0-124.8.1.el10_1 RHSA-2025:20095

AlmaLinux

Errata ↗
ReleasePackageFixed inAdvisory
AlmaLinux 10 rv +74 6.12.0-124.8.1.el10_1 ALSA-2025:20095

Rocky Linux

Errata ↗
ReleasePackageFixed inAdvisory
Rocky Linux 10 kernel 6.12.0-124.8.1.el10_1 RLSA-2025:20095
ReleasePackageFixed inAdvisory
SLES 15 SP6 kernel-64kb +6 6.4.0-150600.23.38.1 SUSE-SU-2025:0499-1
SLES 15 SP6 kernel-azure +2 6.4.0-150600.8.26.1 SUSE-SU-2025:0428-1
SLES 15 SP6 kernel-coco +3 6.4.0-15061.15.coco15sp6.1 SUSE-SU-2025:0564-1
SLES 15 SP6 kernel-default-base 6.4.0-150600.23.38.1.150600.12.16.2 SUSE-SU-2025:0499-1
Show 4 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLE Micro 6.1 kernel-default-base 6.4.0-24.1.21.4 SUSE-SU-2025:20248-1
SLE Micro 6.1 kernel-livepatch-MICRO-6-0-RT_Update_5 1-1.1 SUSE-SU-2025:20249-1
SLE Micro 6.1 kernel-livepatch-MICRO-6-0_Update_5 1-1.2 SUSE-SU-2025:20248-1
SLE Micro 6.1 kernel-rt +4 6.4.0-25.1 SUSE-SU-2025:20249-1, SUSE-SU-2025:20248-1
SLE Micro 6.0 kernel-default-base 6.4.0-24.1.21.4 SUSE-SU-2025:20165-1
SLE Micro 6.0 kernel-livepatch-MICRO-6-0-RT_Update_5 1-1.1 SUSE-SU-2025:20166-1
SLE Micro 6.0 kernel-livepatch-MICRO-6-0_Update_5 1-1.2 SUSE-SU-2025:20165-1
SLE Micro 6.0 kernel-rt +4 6.4.0-25.1 SUSE-SU-2025:20166-1, SUSE-SU-2025:20165-1
SLE Live Patching 15 SP6 kernel-default 6.4.0-150600.23.38.1 SUSE-SU-2025:0499-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6-RT_Update_8 1-150600.1.3.1 SUSE-SU-2025:0557-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6_Update_8 1-150600.13.3.2 SUSE-SU-2025:0499-1
SUSE Real Time Module 15 SP6 kernel-rt +3 6.4.0-150600.10.26.1 SUSE-SU-2025:0557-1
ReleasePackageFixed inAdvisory
openSUSE Leap 15.6 dtb-aarch64 +10 6.4.0-150600.23.38.1 SUSE-SU-2025:0499-1
openSUSE Leap 15.6 kernel-azure +2 6.4.0-150600.8.26.1 SUSE-SU-2025:0428-1
openSUSE Leap 15.6 kernel-default-base 6.4.0-150600.23.38.1.150600.12.16.2 SUSE-SU-2025:0499-1
openSUSE Leap 15.6 kernel-rt +3 6.4.0-150600.10.26.1 SUSE-SU-2025:0557-1

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 kernel-livepatch-6.1.127-135.201 1.0-0.amzn2023 ALAS2023-2025-823
Amazon Linux 2023 perf +14 6.1.127-135.201.amzn2023 ALAS2023-2025-823

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 9 kernel-uek +34 6.12.0-101.33.4.3.el10uek ELSA-2025-20530, ELSA-2025-20480

Advisories 35

References