CVE-2026-43418

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2026-43418
In the Linux kernel, the following vulnerability has been resolved: sched/mmcid: Prevent CID stalls due to concurrent forks A newly forked task is accounted as MMCID user before the task is visible in the process' thread list and the global task list. This creates the following problem: CPU1 CPU2 fork() sched_mm_cid_fork(tnew1) tnew1->mm.mm_cid_users++; tnew1->mm_cid.cid = getcid() -> preemption fork() sched_mm_cid_fork(tnew2) tnew2->mm.mm_cid_users++; // Reaches the per CPU threshold mm_cid_fixup_tasks_to_cpus() for_each_other(current, p) .... As tnew1 is not visible yet, this fails to fix up the already allocated CID of tnew1. As a consequence a subsequent schedule in might fail to acquire a (transitional) CID and the machine stalls. Move the invocation of sched_mm_cid_fork() after the new task becomes visible in the thread and the task list to prevent this. This also makes it symmetrical vs. exit() where the task is removed as CID user before the task is removed from the thread and task lists.

5.5 /10

CVSS v3 : MEDIUM

V3 Legend

Vector :

Exploitability : 1.8 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References
Link Resource
https://git.kernel.org/stable/c/b2e48c429ec54715d16fefa719dd2fbded2e65be Patch
https://git.kernel.org/stable/c/f0189d49282e0458f3a737bd486c1ec048148f66 Patch
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*
History

11 Nov 2026, 20:10

Type Values Removed Values Added
Summary
  • (es) En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta: sched/mmcid: Prevenir bloqueos de CID debido a bifurcaciones concurrentes Una tarea recién bifurcada se contabiliza como usuario de MMCID antes de que la tarea sea visible en la lista de hilos del proceso y en la lista global de tareas. Esto crea el siguiente problema: CPU1 CPU2 fork() sched_mm_cid_fork(tnew1) tnew1 -> mm.mm_cid_users++; tnew1 -> mm_cid.cid = getcid() -> preemption fork() sched_mm_cid_fork(tnew2) tnew2 -> mm.mm_cid_users++; // Reaches the per CPU threshold mm_cid_fixup_tasks_to_cpus() for_each_other(current, p) .... Como tnew1 aún no es visible, esto no logra corregir el CID ya asignado de tnew1. Como consecuencia, una planificación posterior podría no lograr adquirir un CID (transitorio) y la máquina se bloquea. Mover la invocación de sched_mm_cid_fork() después de que la nueva tarea se vuelva visible en la lista de hilos y en la lista de tareas para prevenir esto. Esto también lo hace simétrico frente a exit() donde la tarea se elimina como usuario de CID antes de que la tarea sea eliminada de las listas de hilos y tareas.
Information

Published : 2026-05-08 15:16

Updated : 2026-11-11 20:10

NVD link : CVE-2026-43418

Mitre link : CVE-2026-43418

CVE.ORG link : CVE-2026-43418

JSON object : View

Products Affected

linux

  • linux_kernel
CWE
NVD-CWE-noinfo