CVE-2021-47192
Vulnérabilité moyenne dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: scsi: core: sysfs: Fix hang when device state is set via sysfs This fixes a regression added with: commit f0f82e2476f6 ("scsi: core: Fix capacity set to zero after offlinining device") The problem is that after iSCSI recovery, iscsid will call into the kernel to set the dev's state to running, and with that patch we now call scsi_rescan_device() with the state_mutex held. If the SCSI error handler thread is just starting to test the device in scsi_send_eh_cmnd() then it's going to try to grab the state_mutex. We are then stuck, because when scsi_rescan_device() tries to send its I/O scsi_queue_rq() calls -> scsi_host_queue_ready() -> scsi_host_in_recovery() which will return true (the host state is still in recovery) and I/O will just be requeued. scsi_send_eh_cmnd() will then never be able to grab the state_mutex to finish error handling. To prevent the deadlock move the rescan-related code to after we drop the state_mutex. This also adds a check for if we are already in the running state. This prevents extra scans and helps the iscsid case where if the transport class has already onlined the device during its recovery process then we don't need userspace to do it again plus possibly block that daemon.
Gravité et risque d'exploitation
CVE-2021-47192 obtient un score CVSS de 5.3/10, soit une gravité moyenne. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.61 %, ce qui la place devant 48.3 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions 5.16, c6751ce1a2a415a78e4f5b621628da03196b804c, 0, <edd783162bf2385b43de6764f2d4c6e9f4f6be27, <5.4.162, 711459514e297d748f15ba1f5292a3276c3d1dd0, <5.14, <a792e0128d232251edb5fdf42fb0f9fbb0b44a73, 5.10.61, 69aa1a1a569f5c6d554b59352130ef363342ed4c, <=5.10.*, 5.14, 5.4.162, f0f82e2476f6adb9c7a0135cfab8091456990c99, 5.10.82, 5.15.5, <=5.4.*, 5.13.13, <=*, <bcc0e3175a976b7fa9a353960808adb0bb49ead8, <=5.15.*, <4edd8cd4e86dd3047e5294bbefcc0a08f66a430f, <5.10.82, 5.4.143) 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.