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gh-148252: Avoid overflow in _remote_debugging binary reader bounds checks #148972

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gh-148252: Avoid overflow in _remote_debugging binary reader bounds checks #148972

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2ed6eb1
cannot be simpler?
maurycy Apr 24, 2026
3538dc3
blurb
maurycy Apr 24, 2026
70e11ce
gqgq
maurycy Apr 24, 2026
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Security/2026-04-24-23-15-42.gh-issue-148252.8BLmzd.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Fixed string table and sample record bounds checks in :mod:`!_remote_debugging`
when decoding certain ``.pyb`` inputs on 32-bit builds. Patch by Maurycy
Pawłowski-Wieroński.
7 changes: 4 additions & 3 deletions Modules/_remote_debugging/binary_io_reader.c
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@

/* File structure sizes */
#define FILE_FOOTER_SIZE 32
#define SAMPLE_RECORD_HEADER_SIZE (sizeof(uint64_t) + sizeof(uint32_t) + 1)
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@maurycy maurycy Apr 24, 2026

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There's already SAMPLE_HEADER_FIXED_SIZE:

but it's hard-coded 13. Maybe it should be changed to this addition?

grep for 13 yields more results:

It looks that there's opportunity to move it to binary_io.h. Makes sense, @pablogsal ?

#define MIN_DECOMPRESS_BUFFER_SIZE (64 * 1024) /* Minimum decompression buffer */

/* Progress callback frequency */
Expand Down Expand Up @@ -258,7 +259,7 @@ reader_parse_string_table(BinaryReader *reader, const uint8_t *data, size_t file
PyErr_SetString(PyExc_ValueError, "Malformed varint in string table");
return -1;
}
if (offset + str_len > file_size) {
if (offset > file_size || str_len > file_size - offset) {
PyErr_SetString(PyExc_ValueError, "String table overflow");
return -1;
}
Expand Down Expand Up @@ -976,8 +977,8 @@ binary_reader_replay(BinaryReader *reader, PyObject *collector, PyObject *progre
}

while (offset < reader->sample_data_size) {
/* Read thread_id (8 bytes) + interpreter_id (4 bytes) */
if (offset + 13 > reader->sample_data_size) {
/* Read thread_id (8 bytes) + interpreter_id (4 bytes) + encoding byte */
if (reader->sample_data_size - offset < SAMPLE_RECORD_HEADER_SIZE) {
break; /* End of data */
}

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