Improper locking in Linux kernel - CVE-2021-46921

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Main Vulnerability Database Vulnerabilities #VU88214

Improper locking in Linux kernel - CVE-2021-46921

Published: April 8, 2024 / Updated: May 14, 2025


Vulnerability identifier: #VU88214
CSH Severity: Low
CVSS v4 BT: 4.3 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]
CVE-ID: CVE-2021-46921
CWE-ID: CWE-667
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to perform a denial of service attack.

The vulnerability exists due to improper locking within the queued_write_lock_slowpath() function in kernel/locking/qrwlock.c. A local user can crash the kernel.


Affected software

Linux kernel
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise High Availability Extension 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Manager Server
SUSE Manager Retail Branch Server
SUSE Manager Proxy
SUSE Linux Enterprise Micro
SUSE Linux Enterprise Micro for Rancher
SUSE Enterprise Storage
SUSE Linux Enterprise Server 15 SP2 LTSS
SUSE Linux Enterprise Server 15 SP2 Business Critical Linux
SUSE Linux Enterprise Live Patching
SUSE Linux Enterprise High Performance Computing 15 SP2 LTSS
SUSE Linux Enterprise Server 15 SP3 Business Critical Linux
SUSE Linux Enterprise Server 15 SP3 LTSS
openSUSE Leap
Dell Data Protection Central
PowerProtect DP Series Appliance (IDPA)
Storage Resource Manager
kernel-livepatch-5_3_18-150200_24_188-default
kernel-livepatch-SLE15-SP2_Update_47-debugsource
kernel-livepatch-5_3_18-150200_24_188-default-debuginfo
kernel-livepatch-5_3_18-150300_59_158-preempt
kernel-livepatch-5_3_18-150300_59_158-preempt-debuginfo
kernel-livepatch-SLE15-SP3_Update_43-debugsource
kernel-livepatch-5_3_18-150300_59_158-default
kernel-livepatch-5_3_18-150300_59_158-default-debuginfo
kernel-obs-build-debugsource
kernel-default
kernel-default-devel-debuginfo
kernel-obs-build
kernel-default-devel
kernel-preempt-debuginfo
kernel-macros
kernel-devel
kernel-source
kernel-docs
reiserfs-kmp-default
reiserfs-kmp-default-debuginfo
kernel-syms
kernel-preempt-devel
ocfs2-kmp-default
gfs2-kmp-default
kernel-default-debugsource
kernel-default-livepatch
kernel-default-debuginfo
kernel-default-livepatch-devel
cluster-md-kmp-default
gfs2-kmp-default-debuginfo
ocfs2-kmp-default-debuginfo
dlm-kmp-default
dlm-kmp-default-debuginfo
cluster-md-kmp-default-debuginfo
kernel-preempt
kernel-preempt-devel-debuginfo
kernel-preempt-debugsource
kernel-default-base
ocfs2-kmp-preempt-debuginfo
kselftests-kmp-preempt-debuginfo
kernel-zfcpdump
kernel-zfcpdump-debuginfo
kernel-zfcpdump-debugsource
dtb-aarch64
dtb-qcom
dtb-sprd
dtb-renesas
dtb-freescale
dtb-hisilicon
kselftests-kmp-64kb
dtb-allwinner
kernel-preempt-optional
cluster-md-kmp-preempt
kernel-preempt-livepatch-devel
gfs2-kmp-preempt
reiserfs-kmp-preempt-debuginfo
kselftests-kmp-preempt
kernel-preempt-optional-debuginfo
ocfs2-kmp-preempt
kernel-preempt-extra-debuginfo
gfs2-kmp-preempt-debuginfo
kernel-preempt-extra
cluster-md-kmp-preempt-debuginfo
reiserfs-kmp-preempt
dlm-kmp-preempt
dtb-rockchip
gfs2-kmp-64kb
dtb-cavium
dtb-zte
dlm-kmp-64kb-debuginfo
kernel-64kb-livepatch-devel
kernel-64kb-optional
dtb-arm
kernel-64kb-extra
dtb-marvell
reiserfs-kmp-64kb
ocfs2-kmp-64kb-debuginfo
cluster-md-kmp-64kb-debuginfo
dlm-kmp-64kb
dtb-apm
dtb-nvidia
dtb-amlogic
gfs2-kmp-64kb-debuginfo
kernel-64kb-extra-debuginfo
ocfs2-kmp-64kb
dtb-mediatek
dtb-socionext
kernel-64kb-optional-debuginfo
reiserfs-kmp-64kb-debuginfo
cluster-md-kmp-64kb
dtb-broadcom
dtb-al
kselftests-kmp-64kb-debuginfo
dtb-xilinx
dtb-exynos
dtb-amd
dtb-altera
dtb-lg
kernel-kvmsmall
kernel-source-vanilla
kernel-docs-html
kernel-64kb-debuginfo
kernel-64kb-devel-debuginfo
kernel-64kb-debugsource
kernel-64kb-devel
kernel-64kb
kernel-debug
kernel-default-extra
dlm-kmp-preempt-debuginfo
kernel-obs-qa
kernel-default-optional-debuginfo
kernel-default-optional
kernel-default-extra-debuginfo
kselftests-kmp-default-debuginfo
kselftests-kmp-default
kernel-kvmsmall-devel-debuginfo
kernel-debug-debugsource
kernel-kvmsmall-debugsource
kernel-debug-devel-debuginfo
kernel-kvmsmall-debuginfo
kernel-kvmsmall-livepatch-devel
kernel-kvmsmall-devel
kernel-debug-devel
kernel-debug-livepatch-devel
kernel-debug-debuginfo
kernel-default-base-rebuild
kernel-source-rt
kernel-rt-debuginfo
kernel-rt-debugsource
kernel-rt
Dell EMC Storage Monitoring and Reporting (SMR)
Dell Secure Connect Gateway

How to mitigate CVE-2021-46921

Install updates from vendor's website.

Linux kernel - addressed in versions 4.19.189, 5.4.115, 5.10.33, 5.11.17, 5.12
kernel-livepatch-5_3_18-150200_24_188-default - update to 1-150200.5.3.3
kernel-livepatch-SLE15-SP2_Update_47-debugsource - update to 1-150200.5.3.3
kernel-livepatch-5_3_18-150200_24_188-default-debuginfo - update to 1-150200.5.3.3
kernel-livepatch-5_3_18-150300_59_158-preempt - update to 1-150300.7.3.5
kernel-livepatch-5_3_18-150300_59_158-preempt-debuginfo - update to 1-150300.7.3.5
kernel-livepatch-SLE15-SP3_Update_43-debugsource - update to 1-150300.7.3.5
kernel-livepatch-5_3_18-150300_59_158-default - update to 1-150300.7.3.5
kernel-livepatch-5_3_18-150300_59_158-default-debuginfo - update to 1-150300.7.3.5
Dell EMC Storage Monitoring and Reporting (SMR) - update to 5.0.1.0
Storage Resource Manager - update to 5.0.1.0
kernel-obs-build-debugsource - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-default - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-default-devel-debuginfo - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-obs-build - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-default-devel - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-preempt-debuginfo - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-macros - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-devel - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-source - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-docs - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
reiserfs-kmp-default - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
reiserfs-kmp-default-debuginfo - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-syms - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-preempt-devel - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
ocfs2-kmp-default - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
gfs2-kmp-default - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-default-debugsource - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-default-livepatch - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-default-debuginfo - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-default-livepatch-devel - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
cluster-md-kmp-default - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
gfs2-kmp-default-debuginfo - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
ocfs2-kmp-default-debuginfo - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
dlm-kmp-default - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
dlm-kmp-default-debuginfo - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
cluster-md-kmp-default-debuginfo - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-preempt - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-preempt-devel-debuginfo - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-preempt-debugsource - addressed in versions 5.3.18-150200.24.188.1, 5.3.18-150300.59.158.1
kernel-default-base - addressed in versions 5.3.18-150200.24.188.1.150200.9.95.3, 5.3.18-150300.59.158.1.150300.18.92.5
ocfs2-kmp-preempt-debuginfo - update to 5.3.18-150300.59.158.1
kselftests-kmp-preempt-debuginfo - update to 5.3.18-150300.59.158.1
kernel-zfcpdump - update to 5.3.18-150300.59.158.1
kernel-zfcpdump-debuginfo - update to 5.3.18-150300.59.158.1
kernel-zfcpdump-debugsource - update to 5.3.18-150300.59.158.1
dtb-aarch64 - update to 5.3.18-150300.59.158.1
dtb-qcom - update to 5.3.18-150300.59.158.1
dtb-sprd - update to 5.3.18-150300.59.158.1
dtb-renesas - update to 5.3.18-150300.59.158.1
dtb-freescale - update to 5.3.18-150300.59.158.1
dtb-hisilicon - update to 5.3.18-150300.59.158.1
kselftests-kmp-64kb - update to 5.3.18-150300.59.158.1
dtb-allwinner - update to 5.3.18-150300.59.158.1
kernel-preempt-optional - update to 5.3.18-150300.59.158.1
cluster-md-kmp-preempt - update to 5.3.18-150300.59.158.1
kernel-preempt-livepatch-devel - update to 5.3.18-150300.59.158.1
gfs2-kmp-preempt - update to 5.3.18-150300.59.158.1
reiserfs-kmp-preempt-debuginfo - update to 5.3.18-150300.59.158.1
kselftests-kmp-preempt - update to 5.3.18-150300.59.158.1
kernel-preempt-optional-debuginfo - update to 5.3.18-150300.59.158.1
ocfs2-kmp-preempt - update to 5.3.18-150300.59.158.1
kernel-preempt-extra-debuginfo - update to 5.3.18-150300.59.158.1
gfs2-kmp-preempt-debuginfo - update to 5.3.18-150300.59.158.1
kernel-preempt-extra - update to 5.3.18-150300.59.158.1
cluster-md-kmp-preempt-debuginfo - update to 5.3.18-150300.59.158.1
reiserfs-kmp-preempt - update to 5.3.18-150300.59.158.1
dlm-kmp-preempt - update to 5.3.18-150300.59.158.1
dtb-rockchip - update to 5.3.18-150300.59.158.1
gfs2-kmp-64kb - update to 5.3.18-150300.59.158.1
dtb-cavium - update to 5.3.18-150300.59.158.1
dtb-zte - update to 5.3.18-150300.59.158.1
dlm-kmp-64kb-debuginfo - update to 5.3.18-150300.59.158.1
kernel-64kb-livepatch-devel - update to 5.3.18-150300.59.158.1
kernel-64kb-optional - update to 5.3.18-150300.59.158.1
dtb-arm - update to 5.3.18-150300.59.158.1
kernel-64kb-extra - update to 5.3.18-150300.59.158.1
dtb-marvell - update to 5.3.18-150300.59.158.1
reiserfs-kmp-64kb - update to 5.3.18-150300.59.158.1
ocfs2-kmp-64kb-debuginfo - update to 5.3.18-150300.59.158.1
cluster-md-kmp-64kb-debuginfo - update to 5.3.18-150300.59.158.1
dlm-kmp-64kb - update to 5.3.18-150300.59.158.1
dtb-apm - update to 5.3.18-150300.59.158.1
dtb-nvidia - update to 5.3.18-150300.59.158.1
dtb-amlogic - update to 5.3.18-150300.59.158.1
gfs2-kmp-64kb-debuginfo - update to 5.3.18-150300.59.158.1
kernel-64kb-extra-debuginfo - update to 5.3.18-150300.59.158.1
ocfs2-kmp-64kb - update to 5.3.18-150300.59.158.1
dtb-mediatek - update to 5.3.18-150300.59.158.1
dtb-socionext - update to 5.3.18-150300.59.158.1
kernel-64kb-optional-debuginfo - update to 5.3.18-150300.59.158.1
reiserfs-kmp-64kb-debuginfo - update to 5.3.18-150300.59.158.1
cluster-md-kmp-64kb - update to 5.3.18-150300.59.158.1
dtb-broadcom - update to 5.3.18-150300.59.158.1
dtb-al - update to 5.3.18-150300.59.158.1
kselftests-kmp-64kb-debuginfo - update to 5.3.18-150300.59.158.1
dtb-xilinx - update to 5.3.18-150300.59.158.1
dtb-exynos - update to 5.3.18-150300.59.158.1
dtb-amd - update to 5.3.18-150300.59.158.1
dtb-altera - update to 5.3.18-150300.59.158.1
dtb-lg - update to 5.3.18-150300.59.158.1
kernel-kvmsmall - update to 5.3.18-150300.59.158.1
kernel-source-vanilla - update to 5.3.18-150300.59.158.1
kernel-docs-html - update to 5.3.18-150300.59.158.1
kernel-64kb-debuginfo - update to 5.3.18-150300.59.158.1
kernel-64kb-devel-debuginfo - update to 5.3.18-150300.59.158.1
kernel-64kb-debugsource - update to 5.3.18-150300.59.158.1
kernel-64kb-devel - update to 5.3.18-150300.59.158.1
kernel-64kb - update to 5.3.18-150300.59.158.1
kernel-debug - update to 5.3.18-150300.59.158.1
kernel-default-extra - update to 5.3.18-150300.59.158.1
dlm-kmp-preempt-debuginfo - update to 5.3.18-150300.59.158.1
kernel-obs-qa - update to 5.3.18-150300.59.158.1
kernel-default-optional-debuginfo - update to 5.3.18-150300.59.158.1
kernel-default-optional - update to 5.3.18-150300.59.158.1
kernel-default-extra-debuginfo - update to 5.3.18-150300.59.158.1
kselftests-kmp-default-debuginfo - update to 5.3.18-150300.59.158.1
kselftests-kmp-default - update to 5.3.18-150300.59.158.1
kernel-kvmsmall-devel-debuginfo - update to 5.3.18-150300.59.158.1
kernel-debug-debugsource - update to 5.3.18-150300.59.158.1
kernel-kvmsmall-debugsource - update to 5.3.18-150300.59.158.1
kernel-debug-devel-debuginfo - update to 5.3.18-150300.59.158.1
kernel-kvmsmall-debuginfo - update to 5.3.18-150300.59.158.1
kernel-kvmsmall-livepatch-devel - update to 5.3.18-150300.59.158.1
kernel-kvmsmall-devel - update to 5.3.18-150300.59.158.1
kernel-debug-devel - update to 5.3.18-150300.59.158.1
kernel-debug-livepatch-devel - update to 5.3.18-150300.59.158.1
kernel-debug-debuginfo - update to 5.3.18-150300.59.158.1
kernel-default-base-rebuild - update to 5.3.18-150300.59.158.1.150300.18.92.5
kernel-source-rt - update to 5.3.18-150300.166.1
kernel-rt-debuginfo - update to 5.3.18-150300.166.1
kernel-rt-debugsource - update to 5.3.18-150300.166.1
kernel-rt - update to 5.3.18-150300.166.1
Dell Secure Connect Gateway - update to 5.24.00.14

External References

Related Security Bulletins