CVE-2022-49889
Vulnérabilité moyenne dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters() On some machines the number of listed CPUs may be bigger than the actual CPUs that exist. The tracing subsystem allocates a per_cpu directory with access to the per CPU ring buffer via a cpuX file. But to save space, the ring buffer will only allocate buffers for online CPUs, even though the CPU array will be as big as the nr_cpu_ids. With the addition of waking waiters on the ring buffer when closing the file, the ring_buffer_wake_waiters() now needs to make sure that the buffer is allocated (with the irq_work allocated with it) before trying to wake waiters, as it will cause a NULL pointer dereference. While debugging this, I added a NULL check for the buffer itself (which is OK to do), and also NULL pointer checks against buffer->buffers (which is not fine, and will WARN) as well as making sure the CPU number passed in is within the nr_cpu_ids (which is also not fine if it isn't). Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=1204705
Gravité et risque d'exploitation
CVE-2022-49889 obtient un score CVSS de 5.5/10, soit une gravité moyenne. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.20 %, ce qui la place devant 9.4 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions f4f15344110d0b5b8822ac97bc8200e71939c945, <49ca992f6e50d0f46ec9608f44e011cf3121f389, f3ddb74ad0790030c9592229fb14d8c451f4e9a8, <6.0.8, 6.0.3, <b5074df412bf3df9d6ce096b6fa03eb1082d05c9, <5.15.78, 5544f411a4e8bc39e6a444badbac37dd0e0caf0a, <7433632c9ff68a991bd0bc38cabf354e9d2de410, <5.20, 5.15.75, 2475de2bc0de17fb1b24c5e90194f84b5ca70d3e, 5.19.17) 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.