Описание
In the Linux kernel, the following vulnerability has been resolved: dm-verity: disable recursive forward error correction There are two problems with the recursive correction:
- It may cause denial-of-service. In fec_read_bufs, there is a loop that has 253 iterations. For each iteration, we may call verity_hash_for_block recursively. There is a limit of 4 nested recursions - that means that there may be at most 253^4 (4 billion) iterations. Red Hat QE team actually created an image that pushes dm-verity to this limit - and this image just makes the udev-worker process get stuck in the 'D' state.
- It doesn't work. In fec_read_bufs we store data into the variable
"fio->bufs", but fio bufs is shared between recursive invocations, if
"verity_hash_for_block" invoked correction recursively, it would
overwrite partially filled fio->bufs.
A denial-of-service vulnerability was found in the Linux kernel's dm-verity device mapper target. The recursive forward error correction (FEC) implementation allows up to 253^4 (approximately 4 billion) iterations due to nested recursion in fec_read_bufs() and verity_hash_for_block(). A specially crafted dm-verity image can trigger this worst-case behavior, causing the udev-worker process to become stuck in uninterruptible sleep state.
Отчет
This vulnerability was discovered by the Red Hat QE team who created a dm-verity image that triggers the maximum recursion depth. The resulting denial of service causes system processes to hang in D state, affecting system responsiveness. Additionally, the recursive FEC is fundamentally broken as the shared fio->bufs buffer gets overwritten during recursion. Local access to create or mount dm-verity images is required.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Affected | ||
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | 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 |
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Дополнительная информация
Статус:
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: dm-verity: disable recursive forward error correction There are two problems with the recursive correction: 1. It may cause denial-of-service. In fec_read_bufs, there is a loop that has 253 iterations. For each iteration, we may call verity_hash_for_block recursively. There is a limit of 4 nested recursions - that means that there may be at most 253^4 (4 billion) iterations. Red Hat QE team actually created an image that pushes dm-verity to this limit - and this image just makes the udev-worker process get stuck in the 'D' state. 2. It doesn't work. In fec_read_bufs we store data into the variable "fio->bufs", but fio bufs is shared between recursive invocations, if "verity_hash_for_block" invoked correction recursively, it would overwrite partially filled fio->bufs.
In the Linux kernel, the following vulnerability has been resolved: dm-verity: disable recursive forward error correction There are two problems with the recursive correction: 1. It may cause denial-of-service. In fec_read_bufs, there is a loop that has 253 iterations. For each iteration, we may call verity_hash_for_block recursively. There is a limit of 4 nested recursions - that means that there may be at most 253^4 (4 billion) iterations. Red Hat QE team actually created an image that pushes dm-verity to this limit - and this image just makes the udev-worker process get stuck in the 'D' state. 2. It doesn't work. In fec_read_bufs we store data into the variable "fio->bufs", but fio bufs is shared between recursive invocations, if "verity_hash_for_block" invoked correction recursively, it would overwrite partially filled fio->bufs.
In the Linux kernel, the following vulnerability has been resolved: d ...
In the Linux kernel, the following vulnerability has been resolved: dm-verity: disable recursive forward error correction There are two problems with the recursive correction: 1. It may cause denial-of-service. In fec_read_bufs, there is a loop that has 253 iterations. For each iteration, we may call verity_hash_for_block recursively. There is a limit of 4 nested recursions - that means that there may be at most 253^4 (4 billion) iterations. Red Hat QE team actually created an image that pushes dm-verity to this limit - and this image just makes the udev-worker process get stuck in the 'D' state. 2. It doesn't work. In fec_read_bufs we store data into the variable "fio->bufs", but fio bufs is shared between recursive invocations, if "verity_hash_for_block" invoked correction recursively, it would overwrite partially filled fio->bufs.
5.5 Medium
CVSS3