Описание
It was discovered that the eBPF implementation in the Linux kernel did not properly track bounds information for 32 bit registers when performing div and mod operations. A local attacker could use this to possibly execute arbitrary code.
A flaw was found in the Linux kernel’s eBPF verification code, where the eBPF 32-bit div/mod source register truncation could lead to out-of-bounds reads and writes. By default, accessing the eBPF verifier is only possible to privileged users with CAP_SYS_ADMIN. This flaw allows a local user who can run eBPF instructions to crash the system or possibly escalate their privileges on the system. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.
Меры по смягчению последствий
The default Red Hat Enterprise Linux kernel prevents unprivileged users from being able to use eBPF by the kernel.unprivileged_bpf_disabled sysctl. This would require a privileged user with CAP_SYS_ADMIN or root to be able to abuse this flaw reducing its attack space. For the Red Hat Enterprise Linux 7 the eBPF for unprivileged users is always disabled. For the Red Hat Enterprise Linux 8 to confirm the current state, inspect the sysctl with the command:
cat /proc/sys/kernel/unprivileged_bpf_disabled
The setting of 1 would mean that unprivileged users can not use eBPF, mitigating the flaw. A kernel update will be required to mitigate the flaw for the root or users with CAP_SYS_ADMIN capabilities.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Will not fix | ||
| Red Hat Enterprise Linux 7 | kernel-alt | Will not fix | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Will not fix | ||
| Red Hat Enterprise Linux 9 | kernel | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Fixed | RHSA-2021:4140 | 09.11.2021 |
| Red Hat Enterprise Linux 8 | kernel | Fixed | RHSA-2021:4356 | 09.11.2021 |
Показывать по
Дополнительная информация
Статус:
EPSS
7.8 High
CVSS3
Связанные уязвимости
It was discovered that the eBPF implementation in the Linux kernel did not properly track bounds information for 32 bit registers when performing div and mod operations. A local attacker could use this to possibly execute arbitrary code.
It was discovered that the eBPF implementation in the Linux kernel did not properly track bounds information for 32 bit registers when performing div and mod operations. A local attacker could use this to possibly execute arbitrary code.
It was discovered that the eBPF implementation in the Linux kernel did ...
It was discovered that the eBPF implementation in the Linux kernel did not properly track bounds information for 32 bit registers when performing div and mod operations. A local attacker could use this to possibly execute arbitrary code.
Уязвимость подсистемы eBPF ядра операционной системы Linux, позволяющая нарушителю выполнить произвольный код
EPSS
7.8 High
CVSS3