cbcvebase.
CVE-2022-49834
published 2025-05-01

CVE-2022-49834: In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix use-after-free bug of ns_writer on remount If a nilfs2 filesystem is downgraded…

PriorityP339high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.20%
9.8th percentile
In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix use-after-free bug of ns_writer on remount If a nilfs2 filesystem is downgraded to read-only due to metadata corruption on disk and is remounted read/write, or if emergency read-only remount is performed, detaching a log writer and synchronizing the filesystem can be done at the same time. In these cases, use-after-free of the log writer (hereinafter nilfs->ns_writer) can happen as shown in the scenario below: Task1 Task2 -------------------------------- ------------------------------ nilfs_construct_segment nilfs_segctor_sync init_wait init_waitqueue_entry add_wait_queue schedule nilfs_remount (R/W remount case) nilfs_attach_log_writer nilfs_detach_log_writer nilfs_segctor_destroy kfree finish_wait _raw_spin_lock_irqsave __raw_spin_lock_irqsave do_raw_spin_lock debug_spin_lock_before ns_writer is freed by Task2. After Task1 waked up, Task1 accesses nilfs->ns_writer which is already freed. This scenario diagram is based on the Shigeru Yoshida's post [1]. This patch fixes the issue by not detaching nilfs->ns_writer on remount so that this UAF race doesn't happen. Along with this change, this patch also inserts a few necessary read-only checks with superblock instance where only the ns_writer pointer was used to check if the filesystem is read-only.

Affected

22 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.0.10-1 (bookworm)linux 6.0.10-1 (bookworm)
linuxlinux——
linuxlinux>= fe5f171bb272946ce5fbf843ce2f8467d0d41b9a < b2fbf10040216ef5ee270773755fc2f5da65b749b2fbf10040216ef5ee270773755fc2f5da65b749
linuxlinux>= fe5f171bb272946ce5fbf843ce2f8467d0d41b9a < 39a3ed68270b079c6b874d4e4727a512b9b4882c39a3ed68270b079c6b874d4e4727a512b9b4882c
linuxlinux>= fe5f171bb272946ce5fbf843ce2f8467d0d41b9a < b4736ab5542112fe0a40f140a0a0b072954f34dab4736ab5542112fe0a40f140a0a0b072954f34da
linuxlinux>= fe5f171bb272946ce5fbf843ce2f8467d0d41b9a < 9b162e81045266a2d5b44df9dffdf05c54de9cca9b162e81045266a2d5b44df9dffdf05c54de9cca
linuxlinux>= fe5f171bb272946ce5fbf843ce2f8467d0d41b9a < 4feedde5486c07ea79787839153a71ca71329c7d4feedde5486c07ea79787839153a71ca71329c7d
linuxlinux>= fe5f171bb272946ce5fbf843ce2f8467d0d41b9a < afbd1188382a75f6cfe22c0b68533f7f9664f182afbd1188382a75f6cfe22c0b68533f7f9664f182
linuxlinux>= fe5f171bb272946ce5fbf843ce2f8467d0d41b9a < b152300d5a1ba4258dacf9916bff20e6a8c7603bb152300d5a1ba4258dacf9916bff20e6a8c7603b
linuxlinux>= fe5f171bb272946ce5fbf843ce2f8467d0d41b9a < 8cccf05fe857a18ee26e20d11a8455a73ffd4efd8cccf05fe857a18ee26e20d11a8455a73ffd4efd
linuxlinux_kernel< 4.9.3344.9.334
linuxlinux_kernel——
linuxlinux_kernel>= 0 < 5.10.158-15.10.158-1
linuxlinux_kernel>= 0 < 6.0.10-16.0.10-1
linuxlinux_kernel>= 0 < 6.0.10-16.0.10-1
linuxlinux_kernel>= 0 < 6.0.10-16.0.10-1
linuxlinux_kernel>= 4.10 < 4.14.3004.14.300
linuxlinux_kernel>= 4.15 < 4.19.2674.19.267
linuxlinux_kernel>= 4.20 < 5.4.2255.4.225
linuxlinux_kernel>= 5.11 < 5.15.795.15.79
linuxlinux_kernel>= 5.16 < 6.0.96.0.9
linuxlinux_kernel>= 5.5 < 5.10.1555.10.155

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
osv7.8HIGH
vendor_debian7.8HIGH
vendor_redhat7.8HIGH
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.