cbcvebase.
CVE-2021-47637
published 2025-02-26

CVE-2021-47637: In the Linux kernel, the following vulnerability has been resolved: ubifs: Fix deadlock in concurrent rename whiteout and inode writeback Following hung tasks…

PriorityP418medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.19%
8.7th percentile
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

19 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 5.17.3-1 (bookworm)linux 5.17.3-1 (bookworm)
linuxlinux——
linuxlinux>= 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 < 9dddc8211430fb851ddf0b168e3a00c6f66cc1859dddc8211430fb851ddf0b168e3a00c6f66cc185
linuxlinux>= 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 < 37bdf1ad592555ecda1d55b89f6e393e4c0589d137bdf1ad592555ecda1d55b89f6e393e4c0589d1
linuxlinux>= 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 < 83e42a78428fc354f5e2049935b84c8d8d29b78783e42a78428fc354f5e2049935b84c8d8d29b787
linuxlinux>= 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 < c58af8564a7b08757173009030b74baf4b2b762bc58af8564a7b08757173009030b74baf4b2b762b
linuxlinux>= 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 < 70e9090acc32348cedc5def0cd6d5c126efc97b970e9090acc32348cedc5def0cd6d5c126efc97b9
linuxlinux>= 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 < 8b278c8dcfb565cb65eceb62a38cbf7a7c326db58b278c8dcfb565cb65eceb62a38cbf7a7c326db5
linuxlinux>= 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 < afd427048047e8efdedab30e8888044e2be5aa9cafd427048047e8efdedab30e8888044e2be5aa9c
linuxlinux_kernel>= 0 < 5.10.113-15.10.113-1
linuxlinux_kernel>= 0 < 5.17.3-15.17.3-1
linuxlinux_kernel>= 0 < 5.17.3-15.17.3-1
linuxlinux_kernel>= 0 < 5.17.3-15.17.3-1
linuxlinux_kernel>= 4.20 < 5.4.1895.4.189
linuxlinux_kernel>= 4.9 < 4.19.2384.19.238
linuxlinux_kernel>= 5.11 < 5.15.335.15.33
linuxlinux_kernel>= 5.16 < 5.16.195.16.19
linuxlinux_kernel>= 5.17 < 5.17.25.17.2
linuxlinux_kernel>= 5.5 < 5.10.1105.10.110

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.5MEDIUM
vendor_debian5.5MEDIUM
vendor_redhat5.5MEDIUM
Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.