Описание
In the Linux kernel, the following vulnerability has been resolved:
fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info
Hold state of deferred I/O in struct fb_deferred_io_state. Allocate an
instance as part of initializing deferred I/O and remove it only after
the final mapping has been closed. If the fb_info and the contained
deferred I/O meanwhile goes away, clear struct fb_deferred_io_state.info
to invalidate the mapping. Any access will then result in a SIGBUS
signal.
Fixes a long-standing problem, where a device hot-unplug happens while
user space still has an active mapping of the graphics memory. The hot-
unplug frees the instance of struct fb_info. Accessing the memory will
operate on undefined state.
A flaw was found in the Linux kernel's framebuffer device (fbdev) deferred I/O (defio) mechanism. A local user with an active mapping of graphics memory could trigger a device hot-unplug, leading to the system accessing undefined memory. This can result in system instability or a crash, causing a Denial of Service (DoS).
Отчет
fbdev deferred I/O used a mapping-private pointer to fb_info while user space could keep an active mmap after device hot-unplug. If fb_info was freed before the last VMA was closed, later fault or page_mkwrite handling could operate on stale kernel state and trigger a use-after-free. For the CVSS the PR:L is selected because practical triggering requires local access to the framebuffer device and an active mmap, but this does not necessarily require full host root in systems where /dev/fb access is delegated to a local user or graphics group. The issue is not network reachable and normally depends on a hot-unplug or device removal event, so AC:H is appropriate. Impact is at least local denial of service via kernel crash.
Меры по смягчению последствий
Mitigation for this issue is either not available or the currently available options don't 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 | Fix deferred | ||
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Fix deferred |
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Дополнительная информация
Статус:
5.8 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info Hold state of deferred I/O in struct fb_deferred_io_state. Allocate an instance as part of initializing deferred I/O and remove it only after the final mapping has been closed. If the fb_info and the contained deferred I/O meanwhile goes away, clear struct fb_deferred_io_state.info to invalidate the mapping. Any access will then result in a SIGBUS signal. Fixes a long-standing problem, where a device hot-unplug happens while user space still has an active mapping of the graphics memory. The hot- unplug frees the instance of struct fb_info. Accessing the memory will operate on undefined state.
In the Linux kernel, the following vulnerability has been resolved: fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info Hold state of deferred I/O in struct fb_deferred_io_state. Allocate an instance as part of initializing deferred I/O and remove it only after the final mapping has been closed. If the fb_info and the contained deferred I/O meanwhile goes away, clear struct fb_deferred_io_state.info to invalidate the mapping. Any access will then result in a SIGBUS signal. Fixes a long-standing problem, where a device hot-unplug happens while user space still has an active mapping of the graphics memory. The hot- unplug frees the instance of struct fb_info. Accessing the memory will operate on undefined state.
fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info
In the Linux kernel, the following vulnerability has been resolved: f ...
In the Linux kernel, the following vulnerability has been resolved: fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info Hold state of deferred I/O in struct fb_deferred_io_state. Allocate an instance as part of initializing deferred I/O and remove it only after the final mapping has been closed. If the fb_info and the contained deferred I/O meanwhile goes away, clear struct fb_deferred_io_state.info to invalidate the mapping. Any access will then result in a SIGBUS signal. Fixes a long-standing problem, where a device hot-unplug happens while user space still has an active mapping of the graphics memory. The hot- unplug frees the instance of struct fb_info. Accessing the memory will operate on undefined state.
5.8 Medium
CVSS3