Описание
In the Linux kernel, the following vulnerability has been resolved:
fbdev: fix use-after-free in store_modes()
store_modes() replaces a framebuffer's modelist with modes from userspace.
On success it frees the old modelist with fb_destroy_modelist(). Two
fields still point into that freed list.
One pointer is fb_display[i].mode, the mode a console is using.
fbcon_new_modelist() moves these pointers to the new list. It only does so
for consoles still mapped to the framebuffer. An unmapped console is
skipped and keeps its stale pointer. Unbinding fbcon, for example, sets
con2fb_map[i] to -1 but leaves fb_display[i].mode set. An
FBIOPUT_VSCREENINFO ioctl with FB_ACTIVATE_INV_MODE later reaches
fbcon_mode_deleted(). That function reads the stale fb_display[i].mode
through fb_mode_is_equal(). The read is a use-after-free.
The other pointer is fb_info->mode, the current mode. It is set through
the mode sysfs attribute. store_modes() does not update fb_info->mode, so
it is left pointing into the freed list. show_mode(), the attribute's read
handler, dereferences the stale fb_info->mode through mode_string(). The
read is a use-after-free.
Clear both pointers before freeing the list. Commit a1f305893074 ("fbcon:
Set fb_display[i]->mode to NULL when the mode is released") added the
helper fbcon_delete_modelist(). It clears every fb_display[i].mode that
points into a given list. So far it is called only from the unregister
path. Call it from store_modes() too, and set fb_info->mode to NULL.
A flaw was found in the Linux kernel's framebuffer device (fbdev) component. When the store_modes() function replaces a framebuffer's list of display modes, it fails to properly clear old pointers before freeing the old list. This can result in a use-after-free vulnerability, a type of memory corruption. A local user could exploit this to cause system instability or potentially execute arbitrary code.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Not affected | ||
| 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 | Affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Affected | ||
| Red Hat Enterprise Linux 9 | kernel | Affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Affected | ||
| Red Hat Hardened Images | erlang27 | Not affected |
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Дополнительная информация
Статус:
EPSS
7 High
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: fbdev: fix use-after-free in store_modes() store_modes() replaces a framebuffer's modelist with modes from userspace. On success it frees the old modelist with fb_destroy_modelist(). Two fields still point into that freed list. One pointer is fb_display[i].mode, the mode a console is using. fbcon_new_modelist() moves these pointers to the new list. It only does so for consoles still mapped to the framebuffer. An unmapped console is skipped and keeps its stale pointer. Unbinding fbcon, for example, sets con2fb_map[i] to -1 but leaves fb_display[i].mode set. An FBIOPUT_VSCREENINFO ioctl with FB_ACTIVATE_INV_MODE later reaches fbcon_mode_deleted(). That function reads the stale fb_display[i].mode through fb_mode_is_equal(). The read is a use-after-free. The other pointer is fb_info->mode, the current mode. It is set through the mode sysfs attribute. store_modes() does not update fb_info->mode, so it is left pointing in...
In the Linux kernel, the following vulnerability has been resolved: fbdev: fix use-after-free in store_modes() store_modes() replaces a framebuffer's modelist with modes from userspace. On success it frees the old modelist with fb_destroy_modelist(). Two fields still point into that freed list. One pointer is fb_display[i].mode, the mode a console is using. fbcon_new_modelist() moves these pointers to the new list. It only does so for consoles still mapped to the framebuffer. An unmapped console is skipped and keeps its stale pointer. Unbinding fbcon, for example, sets con2fb_map[i] to -1 but leaves fb_display[i].mode set. An FBIOPUT_VSCREENINFO ioctl with FB_ACTIVATE_INV_MODE later reaches fbcon_mode_deleted(). That function reads the stale fb_display[i].mode through fb_mode_is_equal(). The read is a use-after-free. The other pointer is fb_info->mode, the current mode. It is set through the mode sysfs attribute. store_modes() does not update fb_info->mode, so it is left pointing i
In the Linux kernel, the following vulnerability has been resolved: f ...
In the Linux kernel, the following vulnerability has been resolved: fbdev: fix use-after-free in store_modes() store_modes() replaces a framebuffer's modelist with modes from userspace. On success it frees the old modelist with fb_destroy_modelist(). Two fields still point into that freed list. One pointer is fb_display[i].mode, the mode a console is using. fbcon_new_modelist() moves these pointers to the new list. It only does so for consoles still mapped to the framebuffer. An unmapped console is skipped and keeps its stale pointer. Unbinding fbcon, for example, sets con2fb_map[i] to -1 but leaves fb_display[i].mode set. An FBIOPUT_VSCREENINFO ioctl with FB_ACTIVATE_INV_MODE later reaches fbcon_mode_deleted(). That function reads the stale fb_display[i].mode through fb_mode_is_equal(). The read is a use-after-free. The other pointer is fb_info->mode, the current mode. It is set through the mode sysfs attribute. store_modes() does not update fb_info->mode, so it is left pointin...
EPSS
7 High
CVSS3