CVE - CVE-2022-49834

CVE-ID
CVE-2022-49834	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
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 <-- use-after-free While Task1 is sleeping, nilfs->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.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/39a3ed68270b079c6b874d4e4727a512b9b4882c URL:https://git.kernel.org/stable/c/39a3ed68270b079c6b874d4e4727a512b9b4882c MISC:https://git.kernel.org/stable/c/4feedde5486c07ea79787839153a71ca71329c7d URL:https://git.kernel.org/stable/c/4feedde5486c07ea79787839153a71ca71329c7d MISC:https://git.kernel.org/stable/c/8cccf05fe857a18ee26e20d11a8455a73ffd4efd URL:https://git.kernel.org/stable/c/8cccf05fe857a18ee26e20d11a8455a73ffd4efd MISC:https://git.kernel.org/stable/c/9b162e81045266a2d5b44df9dffdf05c54de9cca URL:https://git.kernel.org/stable/c/9b162e81045266a2d5b44df9dffdf05c54de9cca MISC:https://git.kernel.org/stable/c/afbd1188382a75f6cfe22c0b68533f7f9664f182 URL:https://git.kernel.org/stable/c/afbd1188382a75f6cfe22c0b68533f7f9664f182 MISC:https://git.kernel.org/stable/c/b152300d5a1ba4258dacf9916bff20e6a8c7603b URL:https://git.kernel.org/stable/c/b152300d5a1ba4258dacf9916bff20e6a8c7603b MISC:https://git.kernel.org/stable/c/b2fbf10040216ef5ee270773755fc2f5da65b749 URL:https://git.kernel.org/stable/c/b2fbf10040216ef5ee270773755fc2f5da65b749 MISC:https://git.kernel.org/stable/c/b4736ab5542112fe0a40f140a0a0b072954f34da URL:https://git.kernel.org/stable/c/b4736ab5542112fe0a40f140a0a0b072954f34da
Assigning CNA
kernel.org
Date Record Created
20250501	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20250501)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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