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Vulnerability · Published Feb 26, 2025 · Assigned by Linux

CVE-2021-47637ubifs: Fix deadlock in concurrent rename whiteout and inode writeback

Medium 5.5

In plain English

A medium-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.5Medium
Exploit odds (30 days)0.2%top 91.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: ubifs: Fix deadlock in concurrent rename whiteout and inode writeback Following hung tasks: [ 77.028764] task:kworker/u8:4 state:D stack: 0 pid: 132 [ 77.028820] Call Trace: [ 77.029027] schedule+0x8c/0x1b0 [ 77.029067] mutex_lock+0x50/0x60 [ 77.029074] ubifs_write_inode+0x68/0x1f0 [ubifs] [ 77.029117] __writeback_single_inode+0x43c/0x570 [ 77.029128] writeback_sb_inodes+0x259/0x740 [ 77.029148] wb_writeback+0x107/0x4d0 [ 77.029163] wb_workfn+0x162/0x7b0 [ 92.390442] task:aa state:D stack: 0 pid: 1506 [ 92.390448] Call Trace: [ 92.390458] schedule+0x8c/0x1b0 [ 92.390461] wb_wait_for_completion+0x82/0xd0 [ 92.390469] __writeback_inodes_sb_nr+0xb2/0x110 [ 92.390472] writeback_inodes_sb_nr+0x14/0x20 [ 92.390476] ubifs_budget_space+0x705/0xdd0 [ubifs] [ 92.390503] do_rename.cold+0x7f/0x187 [ubifs] [ 92.390549] ubifs_rename+0x8b/0x180 [ubifs] [ 92.390571] vfs_rename+0xdb2/0x1170 [ 92.390580] do_renameat2+0x554/0x770 , are caused by concurrent rename whiteout and inode writeback processes: rename_whiteout(Thread 1) wb_workfn(Thread2) ubifs_rename do_rename lock_4_inodes (Hold ui_mutex) ubifs_budget_space make_free_space shrink_liability __writeback_inodes_sb_nr bdi_split_work_to_wbs (Queue new wb work) wb_do_writeback(wb work) __writeback_single_inode ubifs_write_inode LOCK(ui_mutex) ↑ wb_wait_for_completion (Wait wb work) <-- deadlock! Reproducer (Detail program in [Link]): 1. SYS_renameat2("/mp/dir/file", "/mp/dir/whiteout", RENAME_WHITEOUT) 2. Consume out of space before kernel(mdelay) doing budget for whiteout Fix it by doing whiteout space budget before locking ubifs inodes. BTW, it also fixes wrong goto tag 'out_release' in whiteout budget error handling path(It should at least recover dir i_size and unlock 4 ubifs inodes).

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux5.17.3-1DEBIAN-CVE-2021-47637
Debian:13linux5.17.3-1DEBIAN-CVE-2021-47637
Debian:14linux5.17.3-1DEBIAN-CVE-2021-47637
Ubuntu:22.04:LTSlinux5.15.0-37.39UBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-aws5.15.0-1011.14UBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-azure5.15.0-1010.12UBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-gcp5.15.0-1008.12UBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-gke5.15.0-1008.10UBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-ibm5.15.0-1007.8UBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1008.11UBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-kvm5.15.0-1010.11UBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-37.39UBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-oracle5.15.0-1009.12UBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-raspi5.15.0-1011.13UBUNTU-CVE-2021-47637
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2021-47637
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2021-47637

Affected products (as reported)

VendorProductVersions
Linux Linux 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 – before 9dddc8211430fb851ddf0b168e3a00c6f66cc1859e0a1fff8db56eaaebb74b4a3ef65f86811c4798 – before 37bdf1ad592555ecda1d55b89f6e393e4c0589d19e0a1fff8db56eaaebb74b4a3ef65f86811c4798 – before 83e42a78428fc354f5e2049935b84c8d8d29b7879e0a1fff8db56eaaebb74b4a3ef65f86811c4798 – before c58af8564a7b08757173009030b74baf4b2b762b9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 – before 70e9090acc32348cedc5def0cd6d5c126efc97b99e0a1fff8db56eaaebb74b4a3ef65f86811c4798 – before 8b278c8dcfb565cb65eceb62a38cbf7a7c326db59e0a1fff8db56eaaebb74b4a3ef65f86811c4798 – before afd427048047e8efdedab30e8888044e2be5aa9c
Linux Linux 4.9

Weakness: CWE-667 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

References