CVE-2022-48921
Vulnérabilité non évaluée dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: sched/fair: Fix fault in reweight_entity Syzbot found a GPF in reweight_entity. This has been bisected to commit 4ef0c5c6b5ba ("kernel/sched: Fix sched_fork() access an invalid sched_task_group") There is a race between sched_post_fork() and setpriority(PRIO_PGRP) within a thread group that causes a null-ptr-deref in reweight_entity() in CFS. The scenario is that the main process spawns number of new threads, which then call setpriority(PRIO_PGRP, 0, -20), wait, and exit. For each of the new threads the copy_process() gets invoked, which adds the new task_struct and calls sched_post_fork() for it. In the above scenario there is a possibility that setpriority(PRIO_PGRP) and set_one_prio() will be called for a thread in the group that is just being created by copy_process(), and for which the sched_post_fork() has not been executed yet. This will trigger a null pointer dereference in reweight_entity(), as it will try to access the run queue pointer, which hasn't been set. Before the mentioned change the cfs_rq pointer for the task has been set in sched_fork(), which is called much earlier in copy_process(), before the new task is added to the thread_group. Now it is done in the sched_post_fork(), which is called after that. To fix the issue the remove the update_load param from the update_load param() function and call reweight_task() only if the task flag doesn't have the TASK_NEW flag set.
Gravité et risque d'exploitation
CVE-2022-48921 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 0.17 %, ce qui la place devant 5.7 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions 5.16, 25d40b828fb855ee62e1039c65a666c9afd60786, 5.14.19, <5.15.27, 0, 5.15.27, <589a954daab5e18399860b6c8ffaeaf79844eb20, 5.15.3, 5.16.13, 5.10.80, <=5.10.*, 3869eecf050416a1d19bac60926f6b5d64b0aa58, 5.10.137, <5.15, <e0bcd6b5779352aed88f2e538a82a39f1a7715bb, c85c6fadbef0a3eab41540ea628fa8fe8928c820, <5.16, <13765de8148f71fa795e0a6607de37c49ea5915a, <=5.16.*, <=*, <8f317cd888059c59e2fa924bf4b0957cfa53f78e, <=5.15.*, <5.10.137, 5.17, 4ef0c5c6b5ba1f38f0ea1cedad0cad722f00c14a) 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.