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.
En el kernel de Linux, se resolvió la siguiente vulnerabilidad: NFSD: corrige el desbordamiento del búfer READDIR Si un cliente envía un argumento de recuento READDIR que es demasiado pequeño (digamos, cero), entonces el cálculo del tamaño del búfer en las nuevas funciones auxiliares init_dirlist da como resultado un subdesbordamiento, lo que permite que las funciones de flujo XDR escriban más allá del búfer real. Este cálculo siempre ha sido sospechoso. NFSD nunca ha verificado la cordura del argumento de conteo READDIR, pero los codificadores de entrada antiguos manejaron el problema correctamente. Con las confirmaciones a continuación, la codificación de entrada cambió, exponiendo el desbordamiento a la aritmética del puntero en xdr_reserve_space(). Los clientes NFS modernos intentan recuperar la mayor cantidad de datos posible para cada solicitud READDIR. Además, no tenemos pruebas unitarias que ejerzan el comportamiento de READDIR en el límite inferior de los valores @count. Por lo tanto, este caso se pasó por alto durante las pruebas.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
| Attack Vector | LOCAL |
|---|---|
| Attack Complexity | LOW |
| Privileges Required | LOW |
| User Interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality Impact | HIGH |
| Integrity Impact | HIGH |
| Availability Impact | HIGH |
| Source | Type | Description |
|---|---|---|
| [email protected] | Primary |
en
CWE-120
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd36ab5d580> | Operating System |
| linux | linux_kernel | 5.16 | <built-in method update of dict object at 0x7fd2dbc284c0> | Operating System |
| linux | linux_kernel | 5.16 | <built-in method update of dict object at 0x7fd39c4c1500> | Operating System |
| linux | linux_kernel | 5.16 | <built-in method update of dict object at 0x7fd3855a4600> | Operating System |
| linux | linux_kernel | 5.16 | <built-in method update of dict object at 0x7fd3686d1440> | Operating System |
| linux | linux_kernel | 5.16 | <built-in method update of dict object at 0x7fd3686d2500> | Operating System |
| linux | linux_kernel | 5.16 | <built-in method update of dict object at 0x7fd319e7bc00> | Operating System |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:5.16:rc2:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:5.16:rc3:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:5.16:rc4:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:5.16:rc5:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:5.16:rc6:*:*:*:*:*:* |