74 lines
2.5 KiB
Diff
74 lines
2.5 KiB
Diff
From c0fa8ea4b9a3fc0043e95622dcc4bf0a96199d57 Mon Sep 17 00:00:00 2001
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From: Maks Verver <maks@verver.ch>
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Date: Mon, 9 Jun 2025 20:09:17 +0100
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Subject: [PATCH] [CVE-2025-32414] python: Read at most len/4 characters.
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Fixes #889 by reserving space in the buffer for UTF-8 encoding of text.
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---
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python/libxml.c | 28 ++++++++++++++++++----------
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1 file changed, 18 insertions(+), 10 deletions(-)
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diff --git a/python/libxml.c b/python/libxml.c
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index ef630254..f31e080f 100644
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--- a/python/libxml.c
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+++ b/python/libxml.c
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@@ -287,7 +287,9 @@ xmlPythonFileReadRaw (void * context, char * buffer, int len) {
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#endif
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file = (PyObject *) context;
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if (file == NULL) return(-1);
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- ret = PyEval_CallMethod(file, (char *) "read", (char *) "(i)", len);
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+ /* When read() returns a string, the length is in characters not bytes, so
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+ request at most len / 4 characters to leave space for UTF-8 encoding. */
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+ ret = PyEval_CallMethod(file, (char *) "read", (char *) "(i)", len / 4);
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if (ret == NULL) {
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printf("xmlPythonFileReadRaw: result is NULL\n");
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return(-1);
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@@ -322,10 +324,12 @@ xmlPythonFileReadRaw (void * context, char * buffer, int len) {
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Py_DECREF(ret);
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return(-1);
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}
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- if (lenread > len)
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- memcpy(buffer, data, len);
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- else
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- memcpy(buffer, data, lenread);
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+ if (lenread < 0 || lenread > len) {
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+ printf("xmlPythonFileReadRaw: invalid lenread\n");
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+ Py_DECREF(ret);
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+ return(-1);
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+ }
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+ memcpy(buffer, data, lenread);
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Py_DECREF(ret);
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return(lenread);
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}
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@@ -352,7 +356,9 @@ xmlPythonFileRead (void * context, char * buffer, int len) {
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#endif
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file = (PyObject *) context;
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if (file == NULL) return(-1);
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- ret = PyEval_CallMethod(file, (char *) "io_read", (char *) "(i)", len);
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+ /* When read() returns a string, the length is in characters not bytes, so
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+ request at most len / 4 characters to leave space for UTF-8 encoding. */
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+ ret = PyEval_CallMethod(file, (char *) "io_read", (char *) "(i)", len / 4);
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if (ret == NULL) {
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printf("xmlPythonFileRead: result is NULL\n");
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return(-1);
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@@ -387,10 +393,12 @@ xmlPythonFileRead (void * context, char * buffer, int len) {
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Py_DECREF(ret);
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return(-1);
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}
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- if (lenread > len)
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- memcpy(buffer, data, len);
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- else
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- memcpy(buffer, data, lenread);
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+ if (lenread < 0 || lenread > len) {
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+ printf("xmlPythonFileRead: invalid lenread\n");
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+ Py_DECREF(ret);
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+ return(-1);
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+ }
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+ memcpy(buffer, data, lenread);
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Py_DECREF(ret);
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return(lenread);
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}
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--
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2.49.0
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