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Misconfiguration
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CVE Vulnerabilities

CVE-2021-46972

Missing Release of Memory after Effective Lifetime

Published: Feb 27, 2024 | Modified: Jan 08, 2025
CVSS 3.x
5.5
MEDIUM
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS 2.x
RedHat/V2
RedHat/V3
5.5 LOW
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Ubuntu
MEDIUM
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2021-46972
CWEhttps://cwe.mitre.org/data/definitions/401.html

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

ovl: fix leaked dentry

Since commit 6815f479ca90 (ovl: use only uppermetacopy state in ovl_lookup()), overlayfs doesnt put temporary dentry when there is a metacopy error, which leads to dentry leaks when shutting down the related superblock:

overlayfs: refusing to follow metacopy origin for (/file0) … BUG: Dentry (ptrval){i=3f33,n=file3} still in use (1) [unmount of overlay overlay] … WARNING: CPU: 1 PID: 432 at umount_check.cold+0x107/0x14d CPU: 1 PID: 432 Comm: unmount-overlay Not tainted 5.12.0-rc5 #1 … RIP: 0010:umount_check.cold+0x107/0x14d … Call Trace: d_walk+0x28c/0x950 ? dentry_lru_isolate+0x2b0/0x2b0 ? __kasan_slab_free+0x12/0x20 do_one_tree+0x33/0x60 shrink_dcache_for_umount+0x78/0x1d0 generic_shutdown_super+0x70/0x440 kill_anon_super+0x3e/0x70 deactivate_locked_super+0xc4/0x160 deactivate_super+0xfa/0x140 cleanup_mnt+0x22e/0x370 __cleanup_mnt+0x1a/0x30 task_work_run+0x139/0x210 do_exit+0xb0c/0x2820 ? __kasan_check_read+0x1d/0x30 ? find_held_lock+0x35/0x160 ? lock_release+0x1b6/0x660 ? mm_update_next_owner+0xa20/0xa20 ? reacquire_held_locks+0x3f0/0x3f0 ? __sanitizer_cov_trace_const_cmp4+0x22/0x30 do_group_exit+0x135/0x380 __do_sys_exit_group.isra.0+0x20/0x20 __x64_sys_exit_group+0x3c/0x50 do_syscall_64+0x45/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xae … VFS: Busy inodes after unmount of overlay. Self-destruct in 5 seconds. Have a nice day…

This fix has been tested with a syzkaller reproducer.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

NameVendorStart VersionEnd Version
Linux_kernelLinux5.8 (including)5.10.35 (excluding)
Linux_kernelLinux5.11 (including)5.11.19 (excluding)
Linux_kernelLinux5.12 (including)5.12.2 (excluding)
Red Hat Enterprise Linux 8RedHatkernel-rt-0:4.18.0-553.8.1.rt7.349.el8_10*
Red Hat Enterprise Linux 8RedHatkernel-0:4.18.0-553.8.1.el8_10*
LinuxUbuntubionic*
LinuxUbuntutrusty*
LinuxUbuntuupstream*
LinuxUbuntuxenial*
Linux-allwinner-5.19Ubuntujammy*
Linux-allwinner-5.19Ubuntuupstream*
Linux-awsUbuntubionic*
Linux-awsUbuntutrusty*
Linux-awsUbuntuupstream*
Linux-awsUbuntuxenial*
Linux-aws-5.0Ubuntubionic*
Linux-aws-5.0Ubuntuesm-infra/bionic*
Linux-aws-5.0Ubuntuupstream*
Linux-aws-5.11Ubuntuesm-infra/focal*
Linux-aws-5.11Ubuntufocal*
Linux-aws-5.11Ubuntuupstream*
Linux-aws-5.13Ubuntuesm-infra/focal*
Linux-aws-5.13Ubuntufocal*
Linux-aws-5.13Ubuntuupstream*
Linux-aws-5.15Ubuntuupstream*
Linux-aws-5.19Ubuntujammy*
Linux-aws-5.19Ubuntuupstream*
Linux-aws-5.3Ubuntubionic*
Linux-aws-5.3Ubuntuesm-infra/bionic*
Linux-aws-5.3Ubuntuupstream*
Linux-aws-5.4Ubuntubionic*
Linux-aws-5.4Ubuntuupstream*
Linux-aws-5.8Ubuntuesm-infra/focal*
Linux-aws-5.8Ubuntufocal*
Linux-aws-5.8Ubuntuupstream*
Linux-aws-6.2Ubuntujammy*
Linux-aws-6.2Ubuntuupstream*
Linux-aws-6.5Ubuntuupstream*
Linux-aws-fipsUbuntutrusty*
Linux-aws-fipsUbuntuupstream*
Linux-aws-fipsUbuntuxenial*
Linux-aws-hweUbuntuupstream*
Linux-aws-hweUbuntuxenial*
Linux-azureUbuntubionic*
Linux-azureUbuntuesm-infra/bionic*
Linux-azureUbuntutrusty*
Linux-azureUbuntuupstream*
Linux-azureUbuntuxenial*
Linux-azure-4.15Ubuntubionic*
Linux-azure-4.15Ubuntuupstream*
Linux-azure-5.11Ubuntuesm-infra/focal*
Linux-azure-5.11Ubuntufocal*
Linux-azure-5.11Ubuntuupstream*
Linux-azure-5.13Ubuntuesm-infra/focal*
Linux-azure-5.13Ubuntufocal*
Linux-azure-5.13Ubuntuupstream*
Linux-azure-5.15Ubuntuupstream*
Linux-azure-5.19Ubuntujammy*
Linux-azure-5.19Ubuntuupstream*
Linux-azure-5.3Ubuntubionic*
Linux-azure-5.3Ubuntuesm-infra/bionic*
Linux-azure-5.3Ubuntuupstream*
Linux-azure-5.4Ubuntubionic*
Linux-azure-5.4Ubuntuupstream*
Linux-azure-5.8Ubuntuesm-infra/focal*
Linux-azure-5.8Ubuntufocal*
Linux-azure-5.8Ubuntuupstream*
Linux-azure-6.2Ubuntujammy*
Linux-azure-6.2Ubuntuupstream*
Linux-azure-6.5Ubuntuupstream*
Linux-azure-edgeUbuntubionic*
Linux-azure-edgeUbuntuesm-infra/bionic*
Linux-azure-edgeUbuntuupstream*
Linux-azure-fdeUbuntuesm-infra/focal*
Linux-azure-fdeUbuntufocal*
Linux-azure-fdeUbuntuupstream*
Linux-azure-fde-5.15Ubuntuupstream*
Linux-azure-fde-5.19Ubuntujammy*
Linux-azure-fde-5.19Ubuntuupstream*
Linux-azure-fde-6.2Ubuntujammy*
Linux-azure-fde-6.2Ubuntuupstream*
Linux-azure-fipsUbuntutrusty*
Linux-azure-fipsUbuntuupstream*
Linux-azure-fipsUbuntuxenial*
Linux-bluefieldUbuntuupstream*
Linux-dell300xUbuntubionic*
Linux-dell300xUbuntuupstream*
Linux-fipsUbuntuupstream*
Linux-gcpUbuntubionic*
Linux-gcpUbuntuesm-infra/bionic*
Linux-gcpUbuntuupstream*
Linux-gcpUbuntuxenial*
Linux-gcp-4.15Ubuntubionic*
Linux-gcp-4.15Ubuntuupstream*
Linux-gcp-5.11Ubuntuesm-infra/focal*
Linux-gcp-5.11Ubuntufocal*
Linux-gcp-5.11Ubuntuupstream*
Linux-gcp-5.13Ubuntuesm-infra/focal*
Linux-gcp-5.13Ubuntufocal*
Linux-gcp-5.13Ubuntuupstream*
Linux-gcp-5.15Ubuntuupstream*
Linux-gcp-5.19Ubuntujammy*
Linux-gcp-5.19Ubuntuupstream*
Linux-gcp-5.3Ubuntubionic*
Linux-gcp-5.3Ubuntuesm-infra/bionic*
Linux-gcp-5.3Ubuntuupstream*
Linux-gcp-5.4Ubuntubionic*
Linux-gcp-5.4Ubuntuupstream*
Linux-gcp-5.8Ubuntuesm-infra/focal*
Linux-gcp-5.8Ubuntufocal*
Linux-gcp-5.8Ubuntuupstream*
Linux-gcp-6.2Ubuntujammy*
Linux-gcp-6.2Ubuntuupstream*
Linux-gcp-6.5Ubuntuupstream*
Linux-gcp-fipsUbuntutrusty*
Linux-gcp-fipsUbuntuupstream*
Linux-gcp-fipsUbuntuxenial*
Linux-gkeUbuntuesm-infra/focal*
Linux-gkeUbuntufocal*
Linux-gkeUbuntuupstream*
Linux-gkeUbuntuxenial*
Linux-gke-4.15Ubuntubionic*
Linux-gke-4.15Ubuntuesm-infra/bionic*
Linux-gke-4.15Ubuntuupstream*
Linux-gke-5.0Ubuntubionic*
Linux-gke-5.0Ubuntuupstream*
Linux-gke-5.15Ubuntuesm-infra/focal*
Linux-gke-5.15Ubuntufocal*
Linux-gke-5.15Ubuntuupstream*
Linux-gke-5.3Ubuntubionic*
Linux-gke-5.3Ubuntuupstream*
Linux-gke-5.4Ubuntubionic*
Linux-gke-5.4Ubuntuesm-infra/bionic*
Linux-gke-5.4Ubuntuupstream*
Linux-gkeopUbuntuupstream*
Linux-gkeop-5.15Ubuntuupstream*
Linux-gkeop-5.4Ubuntubionic*
Linux-gkeop-5.4Ubuntuesm-infra/bionic*
Linux-gkeop-5.4Ubuntuupstream*
Linux-hweUbuntubionic*
Linux-hweUbuntuesm-infra/bionic*
Linux-hweUbuntuupstream*
Linux-hweUbuntuxenial*
Linux-hwe-5.11Ubuntuesm-infra/focal*
Linux-hwe-5.11Ubuntufocal*
Linux-hwe-5.11Ubuntuupstream*
Linux-hwe-5.13Ubuntuesm-infra/focal*
Linux-hwe-5.13Ubuntufocal*
Linux-hwe-5.13Ubuntuupstream*
Linux-hwe-5.15Ubuntuupstream*
Linux-hwe-5.19Ubuntujammy*
Linux-hwe-5.19Ubuntuupstream*
Linux-hwe-5.4Ubuntubionic*
Linux-hwe-5.4Ubuntuupstream*
Linux-hwe-5.8Ubuntuesm-infra/focal*
Linux-hwe-5.8Ubuntufocal*
Linux-hwe-5.8Ubuntuupstream*
Linux-hwe-6.2Ubuntujammy*
Linux-hwe-6.2Ubuntuupstream*
Linux-hwe-6.5Ubuntuupstream*
Linux-hwe-edgeUbuntubionic*
Linux-hwe-edgeUbuntuesm-infra/bionic*
Linux-hwe-edgeUbuntuesm-infra/xenial*
Linux-hwe-edgeUbuntuupstream*
Linux-hwe-edgeUbuntuxenial*
Linux-ibmUbuntumantic*
Linux-ibmUbuntuupstream*
Linux-ibm-5.15Ubuntuupstream*
Linux-ibm-5.4Ubuntubionic*
Linux-ibm-5.4Ubuntuupstream*
Linux-intelUbuntuupstream*
Linux-intel-5.13Ubuntuesm-infra/focal*
Linux-intel-5.13Ubuntufocal*
Linux-intel-5.13Ubuntuupstream*
Linux-intel-iotgUbuntuupstream*
Linux-intel-iotg-5.15Ubuntuupstream*
Linux-iotUbuntuupstream*
Linux-kvmUbuntubionic*
Linux-kvmUbuntuupstream*
Linux-kvmUbuntuxenial*
Linux-laptopUbuntuupstream*
Linux-lowlatencyUbuntuupstream*
Linux-lowlatency-hwe-5.15Ubuntuupstream*
Linux-lowlatency-hwe-5.19Ubuntujammy*
Linux-lowlatency-hwe-5.19Ubuntuupstream*
Linux-lowlatency-hwe-6.2Ubuntujammy*
Linux-lowlatency-hwe-6.2Ubuntuupstream*
Linux-lowlatency-hwe-6.5Ubuntuupstream*
Linux-lts-xenialUbuntutrusty*
Linux-lts-xenialUbuntuupstream*
Linux-nvidiaUbuntuupstream*
Linux-nvidia-6.2Ubuntujammy*
Linux-nvidia-6.2Ubuntuupstream*
Linux-nvidia-6.5Ubuntuupstream*
Linux-nvidia-6.8Ubuntuupstream*
Linux-nvidia-lowlatencyUbuntuupstream*
Linux-oemUbuntubionic*
Linux-oemUbuntuesm-infra/bionic*
Linux-oemUbuntuupstream*
Linux-oemUbuntuxenial*
Linux-oem-5.10Ubuntuesm-infra/focal*
Linux-oem-5.10Ubuntufocal*
Linux-oem-5.10Ubuntuupstream*
Linux-oem-5.13Ubuntuesm-infra/focal*
Linux-oem-5.13Ubuntufocal*
Linux-oem-5.13Ubuntuupstream*
Linux-oem-5.14Ubuntuesm-infra/focal*
Linux-oem-5.14Ubuntufocal*
Linux-oem-5.14Ubuntuupstream*
Linux-oem-5.17Ubuntujammy*
Linux-oem-5.17Ubuntuupstream*
Linux-oem-5.6Ubuntuesm-infra/focal*
Linux-oem-5.6Ubuntufocal*
Linux-oem-5.6Ubuntuupstream*
Linux-oem-6.0Ubuntujammy*
Linux-oem-6.0Ubuntuupstream*
Linux-oem-6.1Ubuntujammy*
Linux-oem-6.1Ubuntuupstream*
Linux-oem-6.5Ubuntuupstream*
Linux-oem-6.8Ubuntuupstream*
Linux-oem-osp1Ubuntubionic*
Linux-oem-osp1Ubuntuupstream*
Linux-oracleUbuntubionic*
Linux-oracleUbuntuupstream*
Linux-oracleUbuntuxenial*
Linux-oracle-5.0Ubuntubionic*
Linux-oracle-5.0Ubuntuesm-infra/bionic*
Linux-oracle-5.0Ubuntuupstream*
Linux-oracle-5.11Ubuntuesm-infra/focal*
Linux-oracle-5.11Ubuntufocal*
Linux-oracle-5.11Ubuntuupstream*
Linux-oracle-5.13Ubuntuesm-infra/focal*
Linux-oracle-5.13Ubuntufocal*
Linux-oracle-5.13Ubuntuupstream*
Linux-oracle-5.15Ubuntuupstream*
Linux-oracle-5.3Ubuntubionic*
Linux-oracle-5.3Ubuntuesm-infra/bionic*
Linux-oracle-5.3Ubuntuupstream*
Linux-oracle-5.4Ubuntubionic*
Linux-oracle-5.4Ubuntuupstream*
Linux-oracle-5.8Ubuntuesm-infra/focal*
Linux-oracle-5.8Ubuntufocal*
Linux-oracle-5.8Ubuntuupstream*
Linux-oracle-6.5Ubuntuupstream*
Linux-raspiUbuntuupstream*
Linux-raspi-5.4Ubuntubionic*
Linux-raspi-5.4Ubuntuupstream*
Linux-raspi2Ubuntubionic*
Linux-raspi2Ubuntuesm-infra/focal*
Linux-raspi2Ubuntufocal*
Linux-raspi2Ubuntuupstream*
Linux-raspi2Ubuntuxenial*
Linux-raspi2-5.3Ubuntubionic*
Linux-raspi2-5.3Ubuntuupstream*
Linux-riscvUbuntuesm-infra/focal*
Linux-riscvUbuntufocal*
Linux-riscvUbuntujammy*
Linux-riscvUbuntuupstream*
Linux-riscv-5.11Ubuntuesm-infra/focal*
Linux-riscv-5.11Ubuntufocal*
Linux-riscv-5.11Ubuntuupstream*
Linux-riscv-5.15Ubuntuupstream*
Linux-riscv-5.19Ubuntujammy*
Linux-riscv-5.19Ubuntuupstream*
Linux-riscv-5.8Ubuntuesm-infra/focal*
Linux-riscv-5.8Ubuntufocal*
Linux-riscv-5.8Ubuntuupstream*
Linux-riscv-6.5Ubuntuupstream*
Linux-snapdragonUbuntubionic*
Linux-snapdragonUbuntuupstream*
Linux-snapdragonUbuntuxenial*
Linux-starfiveUbuntuupstream*
Linux-starfive-5.19Ubuntujammy*
Linux-starfive-5.19Ubuntuupstream*
Linux-starfive-6.2Ubuntujammy*
Linux-starfive-6.2Ubuntuupstream*
Linux-starfive-6.5Ubuntuupstream*
Linux-xilinx-zynqmpUbuntuupstream*

Potential Mitigations

  • Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
  • For example, glibc in Linux provides protection against free of invalid pointers.
  • When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
  • To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

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