{"id":"DEBIAN-CVE-2022-49834","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-\u003ens_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) \t\t\t\t       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  \u003c-- use-after-free  While Task1 is sleeping, nilfs-\u003ens_writer is freed by Task2.  After Task1 waked up, Task1 accesses nilfs-\u003ens_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-\u003ens_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.","modified":"2026-09-01T16:05:33.482941470Z","published":"2025-05-01T15:16:06.873Z","upstream":["CVE-2022-49834"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2022-49834"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.0.10-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49834.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.0.10-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49834.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.0.10-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49834.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}