Cloudanix VulnDB

CVE-2021-47585

None

CVSS

—

EPSS

0.3%

Published

Jun 19, 2024

CISA due date

—

Cloudanix analysis

Monitor only SSVC: Track

A bug in the Linux kernel's btrfs file system code can cause memory to be lost over time, which might slow down or crash the computer if not fixed.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Moderate
Impact
Denial Of Service
Component
OS kernel
Class
Memory Corruption
Remediation
Upgrade
Effort
Medium
Patch risk
Low

What it actually does

Unconditional return in an error path of __add_inode_ref without freeing a kmalloc'd buffer for victim_name, causing a memory leak in the btrfs module.

Why it matters to the business

Repeated triggering can lead to kernel memory exhaustion, potentially causing system instability or denial of service on Linux systems using the btrfs filesystem.

How an attack unfolds

An attacker with the ability to perform filesystem operations that invoke the affected backref_in_log error path can repeatedly trigger the leak to deplete memory resources.

How to fix it

Apply the kernel patch that adds the missing kfree(victim_name) before the return in the error path of __add_inode_ref, or upgrade to a Linux kernel version containing the fix.

How to confirm the fix worked

Review the source code of __add_inode_ref to confirm the kfree call is present in both error paths for victim_name allocations.

Typical attack path

  1. Identify a btrfs filesystem mount
  2. Perform operations that cause inode reference additions involving log checks
  3. Trigger backref_in_log to return negative error repeatedly
  4. Observe gradual memory increase without corresponding frees

How to detect it

Monitor kernel memory allocation logs or use memory leak detection tools to identify unfreed allocations related to btrfs inode references; check for repeated calls to backref_in_log without corresponding frees.

What your security team should do

  • Patch affected Linux kernels with the btrfs memory leak fix
  • Monitor system memory usage for unexplained increases on btrfs volumes
  • Limit untrusted access to btrfs filesystems where possible

The record

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix memory leak in __add_inode_ref() Line 1169 (#3) allocates a memory chunk for victim_name by kmalloc(), but when the function returns in line 1184 (#4) victim_name allocated by line 1169 (#3) is not freed, which will lead to a memory leak. There is a similar snippet of code in this function as allocating a memory chunk for victim_name in line 1104 (#1) as well as releasing the memory in line 1116 (#2). We should kfree() victim_name when the return value of backref_in_log() is less than zero and before the function returns in line 1184 (#4). 1057 static inline int __add_inode_ref(struct btrfs_trans_handle *trans, 1058 struct btrfs_root *root, 1059 struct btrfs_path *path, 1060 struct btrfs_root *log_root, 1061 struct btrfs_inode *dir, 1062 struct btrfs_inode *inode, 1063 u64 inode_objectid, u64 parent_objectid, 1064 u64 ref_index, char *name, int namelen, 1065 int *search_done) 1066 { 1104 victim_name = kmalloc(victim_name_len, GFP_NOFS); // #1: kmalloc (victim_name-1) 1105 if (!victim_name) 1106 return -ENOMEM; 1112 ret = backref_in_log(log_root, &search_key, 1113 parent_objectid, victim_name, 1114 victim_name_len); 1115 if (ret < 0) { 1116 kfree(victim_name); // #2: kfree (victim_name-1) 1117 return ret; 1118 } else if (!ret) { 1169 victim_name = kmalloc(victim_name_len, GFP_NOFS); // #3: kmalloc (victim_name-2) 1170 if (!victim_name) 1171 return -ENOMEM; 1180 ret = backref_in_log(log_root, &search_key, 1181 parent_objectid, victim_name, 1182 victim_name_len); 1183 if (ret < 0) { 1184 return ret; // #4: missing kfree (victim_name-2) 1185 } else if (!ret) { 1241 return 0; 1242 }

Affected packages

Ecosystem Package Introduced Fixed
Debian:11 linux 0 5.10.92-1
Debian:12 linux 0 5.15.15-1
Debian:13 linux 0 5.15.15-1
SUSE:Linux Enterprise High Availability Extension 15 SP4 kernel-default 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Availability Extension 15 SP5 kernel-default 0 5.14.21-150500.55.73.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS kernel-64kb 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS kernel-default 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS kernel-default-base 0 5.14.21-150400.24.128.1.150400.24.62.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS kernel-docs 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS kernel-obs-build 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS kernel-source 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS kernel-syms 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS kernel-64kb 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS kernel-default 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS kernel-default-base 0 5.14.21-150400.24.128.1.150400.24.62.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS kernel-docs 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS kernel-obs-build 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS kernel-source 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS kernel-syms 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Live Patching 15 SP4 kernel-default 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Live Patching 15 SP4 kernel-livepatch-SLE15-SP4_Update_29 0 1-150400.9.3.1
SUSE:Linux Enterprise Live Patching 15 SP5 kernel-default 0 5.14.21-150500.55.73.1
SUSE:Linux Enterprise Live Patching 15 SP5 kernel-livepatch-SLE15-SP5-RT_Update_17 0 1-150500.11.3.1
SUSE:Linux Enterprise Live Patching 15 SP5 kernel-livepatch-SLE15-SP5_Update_17 0 1-150500.11.3.1
SUSE:Linux Enterprise Micro 5.3 kernel-default 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Micro 5.3 kernel-default-base 0 5.14.21-150400.24.128.1.150400.24.62.1
SUSE:Linux Enterprise Micro 5.3 kernel-rt 0 5.14.21-150400.15.88.1
SUSE:Linux Enterprise Micro 5.3 kernel-source-rt 0 5.14.21-150400.15.88.1
SUSE:Linux Enterprise Micro 5.4 kernel-default 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Micro 5.4 kernel-default-base 0 5.14.21-150400.24.128.1.150400.24.62.1
SUSE:Linux Enterprise Micro 5.4 kernel-rt 0 5.14.21-150400.15.88.1
SUSE:Linux Enterprise Micro 5.4 kernel-source-rt 0 5.14.21-150400.15.88.1
SUSE:Linux Enterprise Micro 5.5 kernel-default 0 5.14.21-150500.55.73.1
SUSE:Linux Enterprise Micro 5.5 kernel-default-base 0 5.14.21-150500.55.73.1.150500.6.33.8
SUSE:Linux Enterprise Micro 5.5 kernel-rt 0 5.14.21-150500.13.61.1
SUSE:Linux Enterprise Micro 5.5 kernel-source-rt 0 5.14.21-150500.13.61.1
SUSE:Linux Enterprise Module for Basesystem 15 SP5 kernel-64kb 0 5.14.21-150500.55.73.1
SUSE:Linux Enterprise Module for Basesystem 15 SP5 kernel-default 0 5.14.21-150500.55.73.1
SUSE:Linux Enterprise Module for Basesystem 15 SP5 kernel-default-base 0 5.14.21-150500.55.73.1.150500.6.33.8
SUSE:Linux Enterprise Module for Basesystem 15 SP5 kernel-source 0 5.14.21-150500.55.73.1
SUSE:Linux Enterprise Module for Basesystem 15 SP5 kernel-zfcpdump 0 5.14.21-150500.55.73.1
SUSE:Linux Enterprise Module for Development Tools 15 SP5 kernel-docs 0 5.14.21-150500.55.73.2
SUSE:Linux Enterprise Module for Development Tools 15 SP5 kernel-obs-build 0 5.14.21-150500.55.73.1
SUSE:Linux Enterprise Module for Development Tools 15 SP5 kernel-source 0 5.14.21-150500.55.73.1
SUSE:Linux Enterprise Module for Development Tools 15 SP5 kernel-syms 0 5.14.21-150500.55.73.1
SUSE:Linux Enterprise Module for Legacy 15 SP5 kernel-default 0 5.14.21-150500.55.73.1
SUSE:Linux Enterprise Module for Public Cloud 15 SP5 kernel-azure 0 5.14.21-150500.33.60.1
SUSE:Linux Enterprise Module for Public Cloud 15 SP5 kernel-source-azure 0 5.14.21-150500.33.60.1
SUSE:Linux Enterprise Module for Public Cloud 15 SP5 kernel-syms-azure 0 5.14.21-150500.33.60.1
SUSE:Linux Enterprise Server 15 SP4-LTSS kernel-64kb 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Server 15 SP4-LTSS kernel-default 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Server 15 SP4-LTSS kernel-default-base 0 5.14.21-150400.24.128.1.150400.24.62.1
SUSE:Linux Enterprise Server 15 SP4-LTSS kernel-docs 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Server 15 SP4-LTSS kernel-obs-build 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Server 15 SP4-LTSS kernel-source 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Server 15 SP4-LTSS kernel-syms 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Server 15 SP4-LTSS kernel-zfcpdump 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP4 kernel-default 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP4 kernel-default-base 0 5.14.21-150400.24.128.1.150400.24.62.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP4 kernel-docs 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP4 kernel-obs-build 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP4 kernel-source 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP4 kernel-syms 0 5.14.21-150400.24.128.1
SUSE:Linux Enterprise Workstation Extension 15 SP5 kernel-default 0 5.14.21-150500.55.73.1
SUSE:Manager Proxy 4.3 kernel-default 0 5.14.21-150400.24.128.1
SUSE:Manager Proxy 4.3 kernel-default-base 0 5.14.21-150400.24.128.1.150400.24.62.1
SUSE:Manager Proxy 4.3 kernel-source 0 5.14.21-150400.24.128.1
SUSE:Manager Proxy 4.3 kernel-syms 0 5.14.21-150400.24.128.1
SUSE:Manager Server 4.3 kernel-default 0 5.14.21-150400.24.128.1
SUSE:Manager Server 4.3 kernel-default-base 0 5.14.21-150400.24.128.1.150400.24.62.1
SUSE:Manager Server 4.3 kernel-source 0 5.14.21-150400.24.128.1
SUSE:Manager Server 4.3 kernel-syms 0 5.14.21-150400.24.128.1
SUSE:Manager Server 4.3 kernel-zfcpdump 0 5.14.21-150400.24.128.1
SUSE:Real Time Module 15 SP5 kernel-rt 0 5.14.21-150500.13.61.1
SUSE:Real Time Module 15 SP5 kernel-rt_debug 0 5.14.21-150500.13.61.1
SUSE:Real Time Module 15 SP5 kernel-source-rt 0 5.14.21-150500.13.61.1
SUSE:Real Time Module 15 SP5 kernel-syms-rt 0 5.14.21-150500.13.61.1
Ubuntu:16.04:LTS linux-hwe-edge 0 No fix
Ubuntu:18.04:LTS linux-aws-5.0 0 No fix
Ubuntu:18.04:LTS linux-aws-5.3 0 No fix
Ubuntu:18.04:LTS linux-azure 0 No fix
Ubuntu:18.04:LTS linux-azure-5.3 0 No fix
Ubuntu:18.04:LTS linux-azure-edge 0 No fix
Ubuntu:18.04:LTS linux-gcp 0 No fix
Ubuntu:18.04:LTS linux-gcp-5.3 0 No fix
Ubuntu:18.04:LTS linux-gke-4.15 0 No fix
Ubuntu:18.04:LTS linux-gke-5.4 0 No fix
Ubuntu:18.04:LTS linux-gkeop-5.4 0 No fix
Ubuntu:18.04:LTS linux-hwe 0 No fix
Ubuntu:18.04:LTS linux-hwe-edge 0 No fix
Ubuntu:18.04:LTS linux-oem 0 No fix
Ubuntu:18.04:LTS linux-oracle-5.0 0 No fix
Ubuntu:18.04:LTS linux-oracle-5.3 0 No fix
Ubuntu:20.04:LTS linux 0 5.4.0-9.12
Ubuntu:20.04:LTS linux-aws 0 5.4.0-1005.5
Ubuntu:20.04:LTS linux-aws-5.11 0 No fix
Ubuntu:20.04:LTS linux-aws-5.13 0 No fix
Ubuntu:20.04:LTS linux-aws-5.15 0 5.15.0-1014.18~20.04.1
Ubuntu:20.04:LTS linux-aws-5.8 0 No fix
Ubuntu:20.04:LTS linux-azure 0 5.4.0-1006.6
Ubuntu:20.04:LTS linux-azure-5.11 0 No fix
Ubuntu:20.04:LTS linux-azure-5.13 0 No fix
Ubuntu:20.04:LTS linux-azure-5.15 0 5.15.0-1007.8~20.04.1
Ubuntu:20.04:LTS linux-azure-5.8 0 No fix
Ubuntu:20.04:LTS linux-azure-fde 0 No fix
Ubuntu:20.04:LTS linux-azure-fde-5.15 0 5.15.0-1019.24~20.04.1.1
Ubuntu:20.04:LTS linux-bluefield 0 5.4.0-1007.10
Ubuntu:20.04:LTS linux-gcp 0 5.4.0-1005.5
Ubuntu:20.04:LTS linux-gcp-5.11 0 No fix
Ubuntu:20.04:LTS linux-gcp-5.13 0 No fix
Ubuntu:20.04:LTS linux-gcp-5.15 0 5.15.0-1006.9~20.04.1
Ubuntu:20.04:LTS linux-gcp-5.8 0 No fix
Ubuntu:20.04:LTS linux-gke 0 No fix
Ubuntu:20.04:LTS linux-gke-5.15 0 No fix
Ubuntu:20.04:LTS linux-gkeop 0 5.4.0-1008.9
Ubuntu:20.04:LTS linux-gkeop-5.15 0 5.15.0-1003.5~20.04.2
Ubuntu:20.04:LTS linux-hwe-5.11 0 No fix
Ubuntu:20.04:LTS linux-hwe-5.13 0 No fix
Ubuntu:20.04:LTS linux-hwe-5.15 0 5.15.0-33.34~20.04.1
Ubuntu:20.04:LTS linux-hwe-5.8 0 No fix
Ubuntu:20.04:LTS linux-ibm 0 5.4.0-1003.4
Ubuntu:20.04:LTS linux-ibm-5.15 0 5.15.0-1033.36~20.04.1
Ubuntu:20.04:LTS linux-intel-5.13 0 No fix
Ubuntu:20.04:LTS linux-intel-iotg-5.15 0 5.15.0-1003.5~20.04.1
Ubuntu:20.04:LTS linux-iot 0 5.4.0-1001.3
Ubuntu:20.04:LTS linux-kvm 0 5.4.0-1004.4
Ubuntu:20.04:LTS linux-lowlatency-hwe-5.15 0 5.15.0-33.34~20.04.1
Ubuntu:20.04:LTS linux-oem-5.10 0 No fix
Ubuntu:20.04:LTS linux-oem-5.13 0 No fix
Ubuntu:20.04:LTS linux-oem-5.14 0 No fix
Ubuntu:20.04:LTS linux-oem-5.6 0 No fix
Ubuntu:20.04:LTS linux-oracle 0 5.4.0-1005.5
Ubuntu:20.04:LTS linux-oracle-5.11 0 No fix
Ubuntu:20.04:LTS linux-oracle-5.13 0 No fix
Ubuntu:20.04:LTS linux-oracle-5.15 0 5.15.0-1007.9~20.04.1
Ubuntu:20.04:LTS linux-oracle-5.8 0 No fix
Ubuntu:20.04:LTS linux-raspi 0 5.4.0-1007.7
Ubuntu:20.04:LTS linux-raspi2 0 No fix
Ubuntu:20.04:LTS linux-riscv 0 No fix
Ubuntu:20.04:LTS linux-riscv-5.11 0 No fix
Ubuntu:20.04:LTS linux-riscv-5.15 0 5.15.0-1015.17~20.04.1
Ubuntu:20.04:LTS linux-riscv-5.8 0 No fix
Ubuntu:20.04:LTS linux-xilinx-zynqmp 0 5.4.0-1020.24
Ubuntu:22.04:LTS linux 0 5.15.0-17.17
Ubuntu:22.04:LTS linux-allwinner-5.19 0 No fix
Ubuntu:22.04:LTS linux-aws 0 5.15.0-1002.4
Ubuntu:22.04:LTS linux-aws-5.19 0 No fix
Ubuntu:22.04:LTS linux-aws-6.2 0 No fix
Ubuntu:22.04:LTS linux-aws-6.5 0 6.5.0-1008.8~22.04.1
Ubuntu:22.04:LTS linux-azure 0 5.15.0-1001.2
Ubuntu:22.04:LTS linux-azure-5.19 0 No fix
Ubuntu:22.04:LTS linux-azure-6.2 0 No fix
Ubuntu:22.04:LTS linux-azure-6.5 0 6.5.0-1007.7~22.04.1
Ubuntu:22.04:LTS linux-azure-fde 0 5.15.0-1019.24.1
Ubuntu:22.04:LTS linux-azure-fde-5.19 0 No fix
Ubuntu:22.04:LTS linux-azure-fde-6.2 0 No fix
Ubuntu:22.04:LTS linux-gcp 0 5.15.0-1001.3
Ubuntu:22.04:LTS linux-gcp-5.19 0 No fix
Ubuntu:22.04:LTS linux-gcp-6.2 0 No fix
Ubuntu:22.04:LTS linux-gcp-6.5 0 6.5.0-1010.10~22.04.3
Ubuntu:22.04:LTS linux-gke 0 5.15.0-1002.2
Ubuntu:22.04:LTS linux-gkeop 0 5.15.0-1001.2
Ubuntu:22.04:LTS linux-hwe-5.19 0 No fix
Ubuntu:22.04:LTS linux-hwe-6.2 0 No fix
Ubuntu:22.04:LTS linux-hwe-6.5 0 6.5.0-14.14~22.04.1
Ubuntu:22.04:LTS linux-ibm 0 5.15.0-1002.2
Ubuntu:22.04:LTS linux-intel-iotg 0 5.15.0-1004.6
Ubuntu:22.04:LTS linux-kvm 0 5.15.0-1002.2
Ubuntu:22.04:LTS linux-lowlatency 0 5.15.0-22.22
Ubuntu:22.04:LTS linux-lowlatency-hwe-5.19 0 No fix
Ubuntu:22.04:LTS linux-lowlatency-hwe-6.2 0 No fix
Ubuntu:22.04:LTS linux-lowlatency-hwe-6.5 0 6.5.0-14.14.1~22.04.1
Ubuntu:22.04:LTS linux-nvidia 0 5.15.0-1005.5
Ubuntu:22.04:LTS linux-nvidia-6.2 0 No fix
Ubuntu:22.04:LTS linux-nvidia-6.5 0 6.5.0-1004.4
Ubuntu:22.04:LTS linux-nvidia-6.8 0 6.8.0-1008.8~22.04.1
Ubuntu:22.04:LTS linux-oem-5.17 0 No fix
Ubuntu:22.04:LTS linux-oem-6.0 0 No fix
Ubuntu:22.04:LTS linux-oem-6.1 0 No fix
Ubuntu:22.04:LTS linux-oem-6.5 0 6.5.0-1003.3
Ubuntu:22.04:LTS linux-oracle 0 5.15.0-1001.3
Ubuntu:22.04:LTS linux-oracle-6.5 0 6.5.0-1013.13~22.04.4
Ubuntu:22.04:LTS linux-raspi 0 5.15.0-1002.2
Ubuntu:22.04:LTS linux-riscv 0 No fix
Ubuntu:22.04:LTS linux-riscv-5.19 0 No fix
Ubuntu:22.04:LTS linux-riscv-6.5 0 6.5.0-17.17.1.1~22.04.1
Ubuntu:22.04:LTS linux-starfive-5.19 0 No fix
Ubuntu:22.04:LTS linux-starfive-6.2 0 No fix
Ubuntu:22.04:LTS linux-starfive-6.5 0 6.5.0-1007.8~22.04.1
Ubuntu:22.04:LTS linux-xilinx-zynqmp 0 5.15.0-1022.26
Ubuntu:24.04:LTS linux 0 6.5.0-9.9
Ubuntu:24.04:LTS linux-aws 0 6.5.0-1008.8
Ubuntu:24.04:LTS linux-azure 0 6.5.0-1007.7
Ubuntu:24.04:LTS linux-gcp 0 6.5.0-1007.7
Ubuntu:24.04:LTS linux-gke 0 6.8.0-1003.5
Ubuntu:24.04:LTS linux-gkeop 0 6.8.0-1001.3
Ubuntu:24.04:LTS linux-ibm 0 6.5.0-1009.9
Ubuntu:24.04:LTS linux-lowlatency 0 6.5.0-9.9.1
Ubuntu:24.04:LTS linux-nvidia 0 6.8.0-1007.7
Ubuntu:24.04:LTS linux-nvidia-lowlatency 0 6.8.0-1009.9.1

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