Описание
In the Linux kernel, the following vulnerability has been resolved:
NFSD: Fix READDIR buffer overflow
If a client sends a READDIR count argument that is too small (say,
zero), then the buffer size calculation in the new init_dirlist
helper functions results in an underflow, allowing the XDR stream
functions to write beyond the actual buffer.
This calculation has always been suspect. NFSD has never sanity-
checked the READDIR count argument, but the old entry encoders
managed the problem correctly.
With the commits below, entry encoding changed, exposing the
underflow to the pointer arithmetic in xdr_reserve_space().
Modern NFS clients attempt to retrieve as much data as possible
for each READDIR request. Also, we have no unit tests that
exercise the behavior of READDIR at the lower bound of @count
values. Thus this case was missed during testing.
CVE-2021-47107 is a flaw in the Linux system that runs file-sharing services (NFS). The problem happened because the system did not properly check how much data it should handle when someone asked to list the contents of a folder. If that request was made with a very small value, the system could become confused and try to use more memory than it should. This mistake could cause the computer to crash, stop responding, or even give an attacker a chance to run harmful code. The issue has since been fixed in newer versions of Linux by adding proper checks to prevent unsafe requests.
Отчет
Red Hat Product Security has rated this bug as moderate as the out of box configuration of NFS protects the process from arbitrary code execution scenarios. There is a risk to availablity on successful exploitation of this bug.
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-rt | Affected | ||
| Red Hat Enterprise Linux 9 | kernel | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Fixed | RHSA-2022:7683 | 08.11.2022 |
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Дополнительная информация
Статус:
EPSS
7.1 High
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect. NFSD has never sanity- checked the READDIR count argument, but the old entry encoders managed the problem correctly. With the commits below, entry encoding changed, exposing the underflow to the pointer arithmetic in xdr_reserve_space(). Modern NFS clients attempt to retrieve as much data as possible for each READDIR request. Also, we have no unit tests that exercise the behavior of READDIR at the lower bound of @count values. Thus this case was missed during testing.
In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect. NFSD has never sanity- checked the READDIR count argument, but the old entry encoders managed the problem correctly. With the commits below, entry encoding changed, exposing the underflow to the pointer arithmetic in xdr_reserve_space(). Modern NFS clients attempt to retrieve as much data as possible for each READDIR request. Also, we have no unit tests that exercise the behavior of READDIR at the lower bound of @count values. Thus this case was missed during testing.
In the Linux kernel, the following vulnerability has been resolved: N ...
In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect. NFSD has never sanity- checked the READDIR count argument, but the old entry encoders managed the problem correctly. With the commits below, entry encoding changed, exposing the underflow to the pointer arithmetic in xdr_reserve_space(). Modern NFS clients attempt to retrieve as much data as possible for each READDIR request. Also, we have no unit tests that exercise the behavior of READDIR at the lower bound of @count values. Thus this case was missed during testing.
Уязвимость компонента NFSD ядра операционной системы Linux, позволяющая нарушителю вызвать отказ в обслуживании
EPSS
7.1 High
CVSS3