Описание
In the Linux kernel, the following vulnerability has been resolved:
fs: don't misleadingly warn during thaw operations
The block device may have been frozen before it was claimed by a
filesystem. Concurrently another process might try to mount that
frozen block device and has temporarily claimed the block device for
that purpose causing a concurrent fs_bdev_thaw() to end up here. The
mounter is already about to abort mounting because they still saw an
elevanted bdev->bd_fsfreeze_count so get_bdev_super() will return
NULL in that case.
For example, P1 calls dm_suspend() which calls into bdev_freeze() before
the block device has been claimed by the filesystem. This brings
bdev->bd_fsfreeze_count to 1 and no call into fs_bdev_freeze() is
required.
Now P2 tries to mount that frozen block device. It claims it and checks
bdev->bd_fsfreeze_count. As it's elevated it aborts mounting.
In the meantime P3 called dm_resume(). P3 sees that the block device is
already claimed by a filesystem and calls into fs_bdev_thaw().
P3 takes a passive reference and realizes that the filesystem isn't
ready yet. P3 puts itself to sleep to wait for the filesystem to become
ready.
P2 now puts the last active reference to the filesystem and marks it as
dying. P3 gets woken, sees that the filesystem is dying and
get_bdev_super() fails.
A flaw was found in the Linux kernel. The block device may be frozen before it is claimed by a filesystem. Concurrently, another process might try to mount that frozen block device and can temporarily claim the block device for that purpose, causing a concurrent fs_bdev_thaw() to end up there. When the mounter sees an elevanted bdev->bd_fsfreeze_count, get_bdev_super() will return NULL. This creates possibility for decreased availability.
Отчет
No Red Hat products are affected by this vulnerability.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Out of support scope | ||
| 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 |
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Дополнительная информация
Статус:
EPSS
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: fs: don't misleadingly warn during thaw operations The block device may have been frozen before it was claimed by a filesystem. Concurrently another process might try to mount that frozen block device and has temporarily claimed the block device for that purpose causing a concurrent fs_bdev_thaw() to end up here. The mounter is already about to abort mounting because they still saw an elevanted bdev->bd_fsfreeze_count so get_bdev_super() will return NULL in that case. For example, P1 calls dm_suspend() which calls into bdev_freeze() before the block device has been claimed by the filesystem. This brings bdev->bd_fsfreeze_count to 1 and no call into fs_bdev_freeze() is required. Now P2 tries to mount that frozen block device. It claims it and checks bdev->bd_fsfreeze_count. As it's elevated it aborts mounting. In the meantime P3 called dm_resume(). P3 sees that the block device is already claimed by a filesystem and ...
In the Linux kernel, the following vulnerability has been resolved: fs: don't misleadingly warn during thaw operations The block device may have been frozen before it was claimed by a filesystem. Concurrently another process might try to mount that frozen block device and has temporarily claimed the block device for that purpose causing a concurrent fs_bdev_thaw() to end up here. The mounter is already about to abort mounting because they still saw an elevanted bdev->bd_fsfreeze_count so get_bdev_super() will return NULL in that case. For example, P1 calls dm_suspend() which calls into bdev_freeze() before the block device has been claimed by the filesystem. This brings bdev->bd_fsfreeze_count to 1 and no call into fs_bdev_freeze() is required. Now P2 tries to mount that frozen block device. It claims it and checks bdev->bd_fsfreeze_count. As it's elevated it aborts mounting. In the meantime P3 called dm_resume(). P3 sees that the block device is already claimed by a filesystem an
In the Linux kernel, the following vulnerability has been resolved: f ...
In the Linux kernel, the following vulnerability has been resolved: fs: don't misleadingly warn during thaw operations The block device may have been frozen before it was claimed by a filesystem. Concurrently another process might try to mount that frozen block device and has temporarily claimed the block device for that purpose causing a concurrent fs_bdev_thaw() to end up here. The mounter is already about to abort mounting because they still saw an elevanted bdev->bd_fsfreeze_count so get_bdev_super() will return NULL in that case. For example, P1 calls dm_suspend() which calls into bdev_freeze() before the block device has been claimed by the filesystem. This brings bdev->bd_fsfreeze_count to 1 and no call into fs_bdev_freeze() is required. Now P2 tries to mount that frozen block device. It claims it and checks bdev->bd_fsfreeze_count. As it's elevated it aborts mounting. In the meantime P3 called dm_resume(). P3 sees that the block device is already claimed by a filesystem...
Уязвимость функции fs_bdev_thaw() модуля fs/super.c ядра операционной системы Linux, позволяющая нарушителю вызвать отказ в обслуживании
EPSS
5.5 Medium
CVSS3