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CVE-2022-49834

Vulnérabilité élevée dans Linux (Linux)

CVSS 7.8 · Élevée
EPSS 0.2%
Linux•Linux•Versions : 6.0.9, 5.4.225, <b2fbf10040216ef5ee270773755fc2f5da65b749, 0, <4feedde5486c07ea79787839153a71ca71329c7d, <2.6.34, <afbd1188382a75f6cfe22c0b68533f7f9664f182, <=4.9.*, <b152300d5a1ba4258dacf9916bff20e6a8c7603b, fe5f171bb272946ce5fbf843ce2f8467d0d41b9a, <=5.10.*, <9b162e81045266a2d5b44df9dffdf05c54de9cca, <=4.14.*, <=6.0.*, 2.6.34, <=5.4.*, 4.14.300, <=4.19.*, <39a3ed68270b079c6b874d4e4727a512b9b4882c, 6.1, 4.19.267, 5.10.155, <=*, <=5.15.*, <b4736ab5542112fe0a40f140a0a0b072954f34da, <8cccf05fe857a18ee26e20d11a8455a73ffd4efd, 4.9.334, 5.15.79

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.

Gravité et risque d'exploitation

CVE-2022-49834 obtient un score CVSS de 7.8/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.22 %, ce qui la place devant 12.1 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions 6.0.9, 5.4.225, <b2fbf10040216ef5ee270773755fc2f5da65b749, 0, <4feedde5486c07ea79787839153a71ca71329c7d, <2.6.34, <afbd1188382a75f6cfe22c0b68533f7f9664f182, <=4.9.*, <b152300d5a1ba4258dacf9916bff20e6a8c7603b, fe5f171bb272946ce5fbf843ce2f8467d0d41b9a, <=5.10.*, <9b162e81045266a2d5b44df9dffdf05c54de9cca, <=4.14.*, <=6.0.*, 2.6.34, <=5.4.*, 4.14.300, <=4.19.*, <39a3ed68270b079c6b874d4e4727a512b9b4882c, 6.1, 4.19.267, 5.10.155, <=*, <=5.15.*, <b4736ab5542112fe0a40f140a0a0b072954f34da, <8cccf05fe857a18ee26e20d11a8455a73ffd4efd, 4.9.334, 5.15.79) est présent sur votre parc.
  • Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
  • À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
  • Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

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