https://github.com/python/cpython/commit/b32c830d444c85421bd2c0c7af494c9d85485a29
commit: b32c830d444c85421bd2c0c7af494c9d85485a29
branch: main
author: Serhiy Storchaka <[email protected]>
committer: serhiy-storchaka <[email protected]>
date: 2026-02-24T11:40:24+02:00
summary:
gh-101178: Fix possible integer overflow in Ascii85 encoder with wrapcol=1
(GH-144778)
It could happen if the size of the input is more than 4/5 of sys.maxsize
(only feasible on 32-bit platforms).
Also simplify the integer overflow checks in the Base64 encoder, and
harmonize them with the code for Ascii85 and Base85.
files:
M Modules/binascii.c
diff --git a/Modules/binascii.c b/Modules/binascii.c
index 3abb90ab38bb7f..e6cd64338064b3 100644
--- a/Modules/binascii.c
+++ b/Modules/binascii.c
@@ -785,22 +785,21 @@ binascii_b2a_base64_impl(PyObject *module, Py_buffer
*data, size_t wrapcol,
* Use unsigned integer arithmetic to avoid signed integer overflow.
*/
size_t out_len = ((size_t)bin_len + 2u) / 3u * 4u;
- if (out_len > PY_SSIZE_T_MAX) {
- goto toolong;
- }
if (wrapcol && out_len) {
/* Each line should encode a whole number of bytes. */
wrapcol = wrapcol < 4 ? 4 : wrapcol / 4 * 4;
out_len += (out_len - 1u) / wrapcol;
- if (out_len > PY_SSIZE_T_MAX) {
- goto toolong;
- }
}
if (newline) {
out_len++;
- if (out_len > PY_SSIZE_T_MAX) {
- goto toolong;
+ }
+ if (out_len > PY_SSIZE_T_MAX) {
+ binascii_state *state = get_binascii_state(module);
+ if (state == NULL) {
+ return NULL;
}
+ PyErr_SetString(state->Error, "Too much data for base64");
+ return NULL;
}
PyBytesWriter *writer = PyBytesWriter_Create(out_len);
if (writer == NULL) {
@@ -841,14 +840,6 @@ binascii_b2a_base64_impl(PyObject *module, Py_buffer
*data, size_t wrapcol,
*ascii_data++ = '\n'; /* Append a courtesy newline */
return PyBytesWriter_FinishWithPointer(writer, ascii_data);
-
-toolong:;
- binascii_state *state = get_binascii_state(module);
- if (state == NULL) {
- return NULL;
- }
- PyErr_SetString(state->Error, "Too much data for base64");
- return NULL;
}
/*[clinic input]
@@ -1046,7 +1037,7 @@ binascii_b2a_ascii85_impl(PyObject *module, Py_buffer
*data, int foldspaces,
if (!pad && (bin_len % 4)) {
out_len -= 4 - (bin_len % 4);
}
- if (wrapcol && out_len) {
+ if (wrapcol && out_len && out_len <= PY_SSIZE_T_MAX) {
out_len += (out_len - 1) / wrapcol;
}
if (out_len > PY_SSIZE_T_MAX) {
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