CVE-2024-27036
Vulnérabilité non évaluée dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: cifs: Fix writeback data corruption cifs writeback doesn't correctly handle the case where cifs_extend_writeback() hits a point where it is considering an additional folio, but this would overrun the wsize - at which point it drops out of the xarray scanning loop and calls xas_pause(). The problem is that xas_pause() advances the loop counter - thereby skipping that page. What needs to happen is for xas_reset() to be called any time we decide we don't want to process the page we're looking at, but rather send the request we are building and start a new one. Fix this by copying and adapting the netfslib writepages code as a temporary measure, with cifs writeback intending to be offloaded to netfslib in the near future. This also fixes the issue with the use of filemap_get_folios_tag() causing retry of a bunch of pages which the extender already dealt with. This can be tested by creating, say, a 64K file somewhere not on cifs (otherwise copy-offload may get underfoot), mounting a cifs share with a wsize of 64000, copying the file to it and then comparing the original file and the copy: dd if=/dev/urandom of=/tmp/64K bs=64k count=1 mount //192.168.6.1/test /mnt -o user=...,pass=...,wsize=64000 cp /tmp/64K /mnt/64K cmp /tmp/64K /mnt/64K Without the fix, the cmp fails at position 64000 (or shortly thereafter).
Gravité et risque d'exploitation
CVE-2024-27036 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.28 %, ce qui la place devant 19.5 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions 6.9, <=*, <844b4e132f57f1333dc79feaa035075a096762e4, <65f2ced695982ccd516196d0a9447d85dbe2eed5, <f3dc1bdb6b0b0693562c7c54a6c28bafa608ba3c, <6.3, 6.7.11, <=6.7.*, 6.8.2, <e45deec35bf7f1f4f992a707b2d04a8c162f2240, <=6.6.*, <=6.8.*, 0, 6.6.23, d08089f649a0cfb2099c8551ac47eef0cc23fdf2, 6.3) 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.