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gh-148178: Validate remote debug offset tables on load #148187

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f6f2faf
gh-148178: Validate remote debug offset tables on load
pablogsal Apr 6, 2026
e5e1f21
Fix integer overflow in binary reader stack decoding on 32-bit platforms
pablogsal Apr 8, 2026
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Security/2026-04-06-13-55-00.gh-issue-148178.Rs7kLm.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Hardened :mod:`!_remote_debugging` by validating remote debug offset tables
before using them to size memory reads or interpret remote layouts.
1 change: 1 addition & 0 deletions Modules/_remote_debugging/_remote_debugging.h
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Original file line number Diff line number Diff line change
Expand Up @@ -417,6 +417,7 @@ extern void cached_code_metadata_destroy(void *ptr);
/* Validation */
extern int is_prerelease_version(uint64_t version);
extern int validate_debug_offsets(struct _Py_DebugOffsets *debug_offsets);
#define PY_REMOTE_DEBUG_INVALID_ASYNC_DEBUG_OFFSETS (-2)

/* ============================================================================
* MEMORY READING FUNCTION DECLARATIONS
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14 changes: 12 additions & 2 deletions Modules/_remote_debugging/asyncio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
******************************************************************************/

#include "_remote_debugging.h"
#include "debug_offsets_validation.h"

/* ============================================================================
* ASYNCIO DEBUG ADDRESS FUNCTIONS
Expand Down Expand Up @@ -71,8 +72,13 @@ read_async_debug(RemoteUnwinderObject *unwinder)
int result = _Py_RemoteDebug_PagedReadRemoteMemory(&unwinder->handle, async_debug_addr, size, &unwinder->async_debug_offsets);
if (result < 0) {
set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to read AsyncioDebug offsets");
return result;
}
return result;
if (_PyRemoteDebug_ValidateAsyncDebugOffsets(&unwinder->async_debug_offsets) < 0) {
set_exception_cause(unwinder, PyExc_RuntimeError, "Invalid AsyncioDebug offsets");
return PY_REMOTE_DEBUG_INVALID_ASYNC_DEBUG_OFFSETS;
}
return 0;
}

int
Expand All @@ -85,7 +91,11 @@ ensure_async_debug_offsets(RemoteUnwinderObject *unwinder)

// Try to load async debug offsets (the target process may have
// loaded asyncio since we last checked)
if (read_async_debug(unwinder) < 0) {
int result = read_async_debug(unwinder);
if (result == PY_REMOTE_DEBUG_INVALID_ASYNC_DEBUG_OFFSETS) {
return -1;
}
if (result < 0) {
PyErr_Clear();
PyErr_SetString(PyExc_RuntimeError, "AsyncioDebug section not available");
set_exception_cause(unwinder, PyExc_RuntimeError,
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32 changes: 20 additions & 12 deletions Modules/_remote_debugging/binary_io_reader.c
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Expand Up @@ -601,6 +601,20 @@ reader_get_or_create_thread_state(BinaryReader *reader, uint64_t thread_id,
* STACK DECODING HELPERS
* ============================================================================ */

/* Validate that final_depth fits in the stack buffer.
* Uses uint64_t to prevent overflow on 32-bit platforms. */
static inline int
validate_stack_depth(ReaderThreadState *ts, uint64_t final_depth)
{
if (final_depth > ts->current_stack_capacity) {
PyErr_Format(PyExc_ValueError,
"Final stack depth %llu exceeds capacity %zu",
(unsigned long long)final_depth, ts->current_stack_capacity);
return -1;
}
return 0;
}

/* Decode a full stack from sample data.
* Updates ts->current_stack and ts->current_stack_depth.
* Returns 0 on success, -1 on error (bounds violation). */
Expand Down Expand Up @@ -658,12 +672,9 @@ decode_stack_suffix(ReaderThreadState *ts, const uint8_t *data,
return -1;
}

/* Validate final depth doesn't exceed capacity */
size_t final_depth = (size_t)shared + new_count;
if (final_depth > ts->current_stack_capacity) {
PyErr_Format(PyExc_ValueError,
"Final stack depth %zu exceeds capacity %zu",
final_depth, ts->current_stack_capacity);
/* Use uint64_t to prevent overflow on 32-bit platforms */
uint64_t final_depth = (uint64_t)shared + new_count;
if (validate_stack_depth(ts, final_depth) < 0) {
return -1;
}

Expand Down Expand Up @@ -713,12 +724,9 @@ decode_stack_pop_push(ReaderThreadState *ts, const uint8_t *data,
}
size_t keep = (ts->current_stack_depth > pop) ? ts->current_stack_depth - pop : 0;

/* Validate final depth doesn't exceed capacity */
size_t final_depth = keep + push;
if (final_depth > ts->current_stack_capacity) {
PyErr_Format(PyExc_ValueError,
"Final stack depth %zu exceeds capacity %zu",
final_depth, ts->current_stack_capacity);
/* Use uint64_t to prevent overflow on 32-bit platforms */
uint64_t final_depth = (uint64_t)keep + push;
if (validate_stack_depth(ts, final_depth) < 0) {
return -1;
}

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