cve-2021-47107
Vulnerability from cvelistv5
Published
2024-03-04 18:15
Modified
2024-08-04 05:24
Severity
Summary
NFSD: Fix READDIR buffer overflow
References
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"nvd": "{\"cve\":{\"id\":\"CVE-2021-47107\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2024-03-04T19:15:18.793\",\"lastModified\":\"2024-06-21T14:15:10.653\",\"vulnStatus\":\"Awaiting Analysis\",\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nNFSD: Fix READDIR buffer overflow\\n\\nIf a client sends a READDIR count argument that is too small (say,\\nzero), then the buffer size calculation in the new init_dirlist\\nhelper functions results in an underflow, allowing the XDR stream\\nfunctions to write beyond the actual buffer.\\n\\nThis calculation has always been suspect. NFSD has never sanity-\\nchecked the READDIR count argument, but the old entry encoders\\nmanaged the problem correctly.\\n\\nWith the commits below, entry encoding changed, exposing the\\nunderflow to the pointer arithmetic in xdr_reserve_space().\\n\\nModern NFS clients attempt to retrieve as much data as possible\\nfor each READDIR request. Also, we have no unit tests that\\nexercise the behavior of READDIR at the lower bound of @count\\nvalues. Thus this case was missed during testing.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: NFSD: corrige el desbordamiento del b\u00fafer READDIR Si un cliente env\u00eda un argumento de recuento READDIR que es demasiado peque\u00f1o (digamos, cero), entonces el c\u00e1lculo del tama\u00f1o del b\u00fafer en las nuevas funciones auxiliares init_dirlist da como resultado un subdesbordamiento, lo que permite que las funciones de flujo XDR escriban m\u00e1s all\u00e1 del b\u00fafer real. Este c\u00e1lculo 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 continuaci\u00f3n, la codificaci\u00f3n de entrada cambi\u00f3, exponiendo el desbordamiento a la aritm\u00e9tica del puntero en xdr_reserve_space(). Los clientes NFS modernos intentan recuperar la mayor cantidad de datos posible para cada solicitud READDIR. Adem\u00e1s, no tenemos pruebas unitarias que ejerzan el comportamiento de READDIR en el l\u00edmite inferior de los valores @count. Por lo tanto, este caso se pas\u00f3 por alto durante las pruebas.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
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