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[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.
This commit is contained in:
Maks Verver 2025-04-08 13:13:55 +02:00 committed by Nick Wellnhofer
parent 1e3fd2677a
commit d765781196
1 changed files with 18 additions and 10 deletions
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28
python/libxml.c
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@ -248,7 +248,9 @@ xmlPythonFileReadRaw (void * context, char * buffer, int len) {
file = (PyObject *) context;
if (file == NULL) return(-1);
ret = PyObject_CallMethod(file, (char *) "read", (char *) "(i)", len);
/* When read() returns a string, the length is in characters not bytes, so
request at most len / 4 characters to leave space for UTF-8 encoding. */
ret = PyObject_CallMethod(file, (char *) "read", (char *) "(i)", len / 4);
if (ret == NULL) {
printf("xmlPythonFileReadRaw: result is NULL\n");
return(-1);
@ -283,10 +285,12 @@ xmlPythonFileReadRaw (void * context, char * buffer, int len) {
Py_DECREF(ret);
return(-1);
}
if (lenread > len)
memcpy(buffer, data, len);
else
memcpy(buffer, data, lenread);
if (lenread < 0 || lenread > len) {
printf("xmlPythonFileReadRaw: invalid lenread\n");
Py_DECREF(ret);
return(-1);
}
memcpy(buffer, data, lenread);
Py_DECREF(ret);
return(lenread);
}
@ -310,7 +314,9 @@ xmlPythonFileRead (void * context, char * buffer, int len) {
file = (PyObject *) context;
if (file == NULL) return(-1);
ret = PyObject_CallMethod(file, (char *) "io_read", (char *) "(i)", len);
/* When io_read() returns a string, the length is in characters not bytes, so
request at most len / 4 characters to leave space for UTF-8 encoding. */
ret = PyObject_CallMethod(file, (char *) "io_read", (char *) "(i)", len / 4);
if (ret == NULL) {
printf("xmlPythonFileRead: result is NULL\n");
return(-1);
@ -345,10 +351,12 @@ xmlPythonFileRead (void * context, char * buffer, int len) {
Py_DECREF(ret);
return(-1);
}
if (lenread > len)
memcpy(buffer, data, len);
else
memcpy(buffer, data, lenread);
if (lenread < 0 || lenread > len) {
printf("xmlPythonFileRead: invalid lenread\n");
Py_DECREF(ret);
return(-1);
}
memcpy(buffer, data, lenread);
Py_DECREF(ret);
return(lenread);
}