Skip to content
CVE PROGRAM SOURCE RECORD7.8 High

CVE-2022-49834

nilfs2: fix use-after-free bug of ns_writer on remount

Read JSON ↗CVE.org ↗
Status
Published
Published
Updated
Assigning organization
Linux

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • fe5f171bb272946ce5fbf843ce2f8467d0d41b9a to < b2fbf10040216ef5ee270773755fc2f5da65b749affected
  • fe5f171bb272946ce5fbf843ce2f8467d0d41b9a to < 39a3ed68270b079c6b874d4e4727a512b9b4882caffected
  • fe5f171bb272946ce5fbf843ce2f8467d0d41b9a to < b4736ab5542112fe0a40f140a0a0b072954f34daaffected
  • fe5f171bb272946ce5fbf843ce2f8467d0d41b9a to < 9b162e81045266a2d5b44df9dffdf05c54de9ccaaffected
  • fe5f171bb272946ce5fbf843ce2f8467d0d41b9a to < 4feedde5486c07ea79787839153a71ca71329c7daffected
  • fe5f171bb272946ce5fbf843ce2f8467d0d41b9a to < afbd1188382a75f6cfe22c0b68533f7f9664f182affected
  • fe5f171bb272946ce5fbf843ce2f8467d0d41b9a to < b152300d5a1ba4258dacf9916bff20e6a8c7603baffected
  • fe5f171bb272946ce5fbf843ce2f8467d0d41b9a to < 8cccf05fe857a18ee26e20d11a8455a73ffd4efdaffected

Linux Linux

Default version status: affected

  • 2.6.34affected
  • 0 to < 2.6.34unaffected
  • 4.9.334 to ≤ 4.9.*unaffected
  • 4.14.300 to ≤ 4.14.*unaffected
  • 4.19.267 to ≤ 4.19.*unaffected
  • 5.4.225 to ≤ 5.4.*unaffected
  • 5.10.155 to ≤ 5.10.*unaffected
  • 5.15.79 to ≤ 5.15.*unaffected
  • 6.0.9 to ≤ 6.0.*unaffected
  • 6.1 to ≤ *unaffected

References