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Fix UTF-8 buffer overflows from code-point string lengths #522

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Fix UTF-8 buffer overflows from code-point string lengths #522

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ba2dc8b
Fix UTF-8 buffer overflows from code-point string lengths
JarrettSJohnson Oct 7, 2026
bb3b28a
Don't print non-ASCII text in wizard prompt test
JarrettSJohnson Oct 7, 2026
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7 changes: 4 additions & 3 deletions layer1/PConv.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -122,10 +122,10 @@ int PConvPyListToStrVLAList(PyObject * obj, char **vla, int *n_str)
for(i = 0; i < n_st; i++) {
t = PyList_GetItem(obj, i);
if(PyString_Check(t)) {
l = PyString_Size(t);
auto strval = PyString_AsSomeString(t);
l = strval.length();
nn_ch = n_ch + l + 1;
VLACheck(*vla, char, nn_ch);
auto strval = PyString_AsSomeString(t);
UtilNCopy((*vla) + n_ch, strval.c_str(), l + 1);
n_ch = nn_ch;
} else {
Expand Down Expand Up @@ -1159,7 +1159,8 @@ int PConvPyListToStringVLA(PyObject * obj, char **vla_ptr)
for(a = 0; a < l; a++) {
i = PyList_GetItem(obj, a);
if(PyString_Check(i)) {
ll += PyString_Size(i) + 1;
// UTF-8 byte length (PyString_Size counts code points)
ll += PyString_AsSomeString(i).length() + 1;
}
}
vla = VLAlloc(char, ll);
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6 changes: 3 additions & 3 deletions layer4/PopUp.cpp
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Expand Up @@ -186,9 +186,9 @@ Block *PopUpNew(PyMOLGlobals * G, int x, int y, int last_x, int last_y,
continue;
}
elem = PyList_GetItem(item, 1);
l = PyString_Size(elem);
str = PyString_AsString(elem);
cl = l;
l = strlen(str); /* buffer size in UTF-8 bytes */
cl = PyString_Size(elem); /* display width in characters */

@speleo3 speleo3 Oct 8, 2026

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Maybe better to remove the legacy macros and to use PyUnicode_GetLength directly?

pymol-open-source/layer0/os_python.h

Lines 47 to 48 in edcda80

# define PyString_Size PyUnicode_GetLength
# define PyString_GET_SIZE PyUnicode_GetLength

c = str;
while(*c) {
if(TextStartsWithColorCode(c)) { /* discount the markup */
Expand All @@ -214,7 +214,7 @@ Block *PopUpNew(PyMOLGlobals * G, int x, int y, int last_x, int last_y,
if (PyList_Size(item) > 2) {
PyObject* command = PyList_GetItem(item, 2);
if(PyString_Check(command)) {
l = PyString_Size(command);
l = strlen(PyString_AsString(command));
if(l > mx)
mx = l;
}
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21 changes: 21 additions & 0 deletions testing/tests/wizard/prompt.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
'''
unit tests for wizard prompts
'''

from pymol import cmd, testing
from pymol.wizard import Wizard

class TestPrompt(testing.PyMOLTestCase):

def test_NonAsciiPrompt(self):
# github #517: prompt buffer was sized by code points instead of
# UTF-8 bytes, overflowing the heap for multi-byte characters.
# Plain Wizard instead of the message wizard, which prints the
# text and fails on non-UTF-8 consoles (e.g. cp1252 on Windows).
wiz = Wizard()
wiz.prompt = ["Unicode test: " + "测试消息" * 2000]
cmd.set_wizard(wiz)
for _ in range(10):
cmd.refresh_wizard()
self.assertIs(cmd.get_wizard(), wiz)
cmd.set_wizard()
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