CVE-2022-49834
- Source
- https://nvd.nist.gov/vuln/detail/CVE-2022-49834
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49834.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2022-49834
- Related
- Published
- 2025-05-01T15:16:06Z
- Modified
- 2025-05-02T14:45:52.518472Z
- Summary
- [none]
- Details
-
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 -------------------------------- ------------------------------ nilfsconstructsegment nilfssegctorsync initwait initwaitqueueentry addwaitqueue schedule nilfsremount (R/W remount case) nilfsattachlogwriter nilfsdetachlogwriter nilfssegctordestroy kfree finishwait _rawspinlockirqsave _rawspinlockirqsave dorawspinlock debugspinlockbefore <-- use-after-free
While Task1 is sleeping, nilfs->nswriter is freed by Task2. After Task1 waked up, Task1 accesses nilfs->nswriter 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->nswriter 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 nswriter pointer was used to check if the filesystem is read-only.
- References
-
- https://git.kernel.org/stable/c/39a3ed68270b079c6b874d4e4727a512b9b4882c
- https://git.kernel.org/stable/c/4feedde5486c07ea79787839153a71ca71329c7d
- https://git.kernel.org/stable/c/8cccf05fe857a18ee26e20d11a8455a73ffd4efd
- https://git.kernel.org/stable/c/9b162e81045266a2d5b44df9dffdf05c54de9cca
- https://git.kernel.org/stable/c/afbd1188382a75f6cfe22c0b68533f7f9664f182
- https://git.kernel.org/stable/c/b152300d5a1ba4258dacf9916bff20e6a8c7603b
- https://git.kernel.org/stable/c/b2fbf10040216ef5ee270773755fc2f5da65b749
- https://git.kernel.org/stable/c/b4736ab5542112fe0a40f140a0a0b072954f34da
- https://security-tracker.debian.org/tracker/CVE-2022-49834
Affected packages
Debian:11 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source
Affected ranges
- Type
- ECOSYSTEM
- Events
-
Introduced0Unknown introduced version / All previous versions are affectedFixed5.10.158-1
Debian:12 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source
Debian:13 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source