Описание
In the Linux kernel, the following vulnerability has been resolved:
exec: do_close_on_exec() before taking exec_update_lock
do_close_on_exec() currently happens while holding the exec_update_lock,
which is used in a lot of places that access process state to
synchronize access checks.
I recently added another such use of exec_update_lock, causing a
regression.
do_close_on_exec() can block waiting for a reply from a filesystem.
That means a hung filesystem can block codepaths that use
exec_update_lock; and it also means that a FUSE filesystem which
attempts to inspect the calling process can deadlock.
To avoid such problems, move do_close_on_exec() before the
exec_update_lock is taken, but after the FD table has been copied if
necessary.
I have looked through all the calls between the old and new position of
the do_close_on_exec() call; there seems to be no file descriptor table
access in between.
A flaw was found in the Linux kernel. During program execution, the kernel closes file descriptors marked for close-on-exec while holding an internal process state lock. If closing a file descriptor stalls on an unresponsive or user-space filesystem, the lock remains held and blocks related system operations. A local attacker can exploit this behavior to trigger a deadlock, resulting in a Denial of Service (DoS).
Отчет
A low impact denial of service flaw was found in the Linux kernel as shipped in Red Hat offerings. During program execution, the kernel closes file descriptors marked for close-on-exec (do_close_on_exec()) while holding exec_update_lock, a lock that is used in many places that access process state to synchronize access checks. Closing a file descriptor can block waiting for a reply from a filesystem, so a hung or unresponsive filesystem keeps the lock held and blocks kernel code paths that use exec_update_lock; a FUSE filesystem whose daemon attempts to inspect the calling process can also deadlock. A local unprivileged attacker can exploit this behavior by triggering program execution with a close-on-exec file descriptor backed by such a filesystem, hanging process execution and related process-state operations and causing a local denial of service. There is no impact on confidentiality or integrity. The Red Hat CVSS:3.1 base score is 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H); while that base score maps to Moderate, Red Hat Product Security assesses the overall impact of this flaw as LOW because exploitation requires local access with a prepared close-on-exec file descriptor on a suitable blocking filesystem and the result is limited to a local denial of service. Of the Red Hat products in scope, only the kernel in the Red Hat Enterprise Linux 6 Extended Lifecycle Support stream is listed as affected, and that stream is out of support scope so no fix is planned for it. The kernels in Red Hat Enterprise Linux 7, 8, 9, and 10 (including the kernel-rt variant), the Red Hat In-Vehicle OS kernels, and the Red Hat Enterprise Linux CoreOS images shipped with OpenShift Container Platform are not affected because the vulnerable code is not present in those kernels.
Меры по смягчению последствий
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Not affected | ||
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Not affected | ||
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-8 | Not affected | ||
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-9 | Not affected |
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Дополнительная информация
Статус:
EPSS
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: exec: do_close_on_exec() before taking exec_update_lock do_close_on_exec() currently happens while holding the exec_update_lock, which is used in a lot of places that access process state to synchronize access checks. I recently added another such use of exec_update_lock, causing a regression. do_close_on_exec() can block waiting for a reply from a filesystem. That means a hung filesystem can block codepaths that use exec_update_lock; and it also means that a FUSE filesystem which attempts to inspect the calling process can deadlock. To avoid such problems, move do_close_on_exec() before the exec_update_lock is taken, but after the FD table has been copied if necessary. I have looked through all the calls between the old and new position of the do_close_on_exec() call; there seems to be no file descriptor table access in between.
In the Linux kernel, the following vulnerability has been resolved: exec: do_close_on_exec() before taking exec_update_lock do_close_on_exec() currently happens while holding the exec_update_lock, which is used in a lot of places that access process state to synchronize access checks. I recently added another such use of exec_update_lock, causing a regression. do_close_on_exec() can block waiting for a reply from a filesystem. That means a hung filesystem can block codepaths that use exec_update_lock; and it also means that a FUSE filesystem which attempts to inspect the calling process can deadlock. To avoid such problems, move do_close_on_exec() before the exec_update_lock is taken, but after the FD table has been copied if necessary. I have looked through all the calls between the old and new position of the do_close_on_exec() call; there seems to be no file descriptor table access in between.
In the Linux kernel, the following vulnerability has been resolved: e ...
In the Linux kernel, the following vulnerability has been resolved: exec: do_close_on_exec() before taking exec_update_lock do_close_on_exec() currently happens while holding the exec_update_lock, which is used in a lot of places that access process state to synchronize access checks. I recently added another such use of exec_update_lock, causing a regression. do_close_on_exec() can block waiting for a reply from a filesystem. That means a hung filesystem can block codepaths that use exec_update_lock; and it also means that a FUSE filesystem which attempts to inspect the calling process can deadlock. To avoid such problems, move do_close_on_exec() before the exec_update_lock is taken, but after the FD table has been copied if necessary. I have looked through all the calls between the old and new position of the do_close_on_exec() call; there seems to be no file descriptor table access in between.
EPSS
5.5 Medium
CVSS3