CVE-2024-50250
Vulnérabilité élevée dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: fsdax: dax_unshare_iter needs to copy entire blocks The code that copies data from srcmap to iomap in dax_unshare_iter is very very broken, which bfoster's recent fsx changes have exposed. If the pos and len passed to dax_file_unshare are not aligned to an fsblock boundary, the iter pos and length in the _iter function will reflect this unalignment. dax_iomap_direct_access always returns a pointer to the start of the kmapped fsdax page, even if its pos argument is in the middle of that page. This is catastrophic for data integrity when iter->pos is not aligned to a page, because daddr/saddr do not point to the same byte in the file as iter->pos. Hence we corrupt user data by copying it to the wrong place. If iter->pos + iomap_length() in the _iter function not aligned to a page, then we fail to copy a full block, and only partially populate the destination block. This is catastrophic for data confidentiality because we expose stale pmem contents. Fix both of these issues by aligning copy_pos/copy_len to a page boundary (remember, this is fsdax so 1 fsblock == 1 base page) so that we always copy full blocks. We're not done yet -- there's no call to invalidate_inode_pages2_range, so programs that have the file range mmap'd will continue accessing the old memory mapping after the file metadata updates have completed. Be careful with the return value -- if the unshare succeeds, we still need to return the number of bytes that the iomap iter thinks we're operating on.
Gravité et risque d'exploitation
CVE-2024-50250 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 0.23 %, ce qui la place devant 12.8 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions 6.12, <=6.1.*, 6.11.7, 6.1.116, 6.6.60, <=6.11.*, 0, d984648e428bf88cbd94ebe346c73632cb92fffb, <6.1.116, <=6.6.*, 6.1.113, <6.2, <=*, <bdbc96c23197d773a7d1bf03e4f11de593b0ff28, <9bc18bb476e50e32e5d08f2734d63d63e0fa528c, <8e9c0f500b42216ef930f5c0d1703989a451913d, <50793801fc7f6d08def48754fb0f0706b0cfc394, 1bec6782a25c9b92c203ea7a1b3e3dc6a468cbc4, 6.2) 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.