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PYTHON-4305 Fix bson size check #1564

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merged 1 commit into from
Mar 27, 2024
Merged

PYTHON-4305 Fix bson size check #1564

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11 changes: 5 additions & 6 deletions bson/_cbsonmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2293,6 +2293,7 @@ static PyObject* get_value(PyObject* self, PyObject* name, const char* buffer,
uint32_t c_w_s_size;
uint32_t code_size;
uint32_t scope_size;
uint32_t len;
PyObject* code;
PyObject* scope;

Expand All @@ -2311,7 +2312,8 @@ static PyObject* get_value(PyObject* self, PyObject* name, const char* buffer,
memcpy(&code_size, buffer + *position, 4);
code_size = BSON_UINT32_FROM_LE(code_size);
/* code_w_scope length + code length + code + scope length */
if (!code_size || max < code_size || max < 4 + 4 + code_size + 4) {
len = 4 + 4 + code_size + 4;
if (!code_size || max < code_size || max < len || len < code_size) {
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len < code_size catches when len overflows.

goto invalid;
}
*position += 4;
Expand All @@ -2329,12 +2331,9 @@ static PyObject* get_value(PyObject* self, PyObject* name, const char* buffer,

memcpy(&scope_size, buffer + *position, 4);
scope_size = BSON_UINT32_FROM_LE(scope_size);
if (scope_size < BSON_MIN_SIZE) {
Py_DECREF(code);
goto invalid;
}
/* code length + code + scope length + scope */
if ((4 + code_size + 4 + scope_size) != c_w_s_size) {
len = 4 + 4 + code_size + scope_size;
if (scope_size < BSON_MIN_SIZE || len != c_w_s_size || len < scope_size) {
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len < scope_size catches when len overflows.

Py_DECREF(code);
goto invalid;
}
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