Resizing bytearray with active memoryviews corrupts state and segfaults
Port, board and/or hardware
Unix
MicroPython version
MicroPython v1.27.0-preview.107.gd1607598f on 2025-09-09; linux [GCC 14.2.0] version
Reproduction
import gc
ba = bytearray(b"abcdefghij")
views = [memoryview(ba) for _ in range(4)]
ba[:] = ba + b"X"*256
gc.collect()
for i, mv in enumerate(views):
mv[0:1] = b"Y"
Expected behaviour
Attempting to resize a bytearray that has active memoryview exports should raise a Python exception and must not corrupt the VM or crash.
Observed behaviour
The resize succeeds; existing memoryviews retain stale pointers to the old buffer. After gc.collect() (or later operations), the VM state gets corrupted and the process segfaults in unrelated code paths (e.g., during enumerate, inside mp_load_method_maybe).
Additional Information
No, I've provided everything above.
Code of Conduct
Yes, I agree
uctypes.bytearray_at() accepts negative address and segfaults on write
Port, board and/or hardware
Unix port
MicroPython version
MicroPython v1.27.0-preview.107.gd1607598f on 2025-09-09; linux [GCC 14.2.0] version
Reproduction
try:
import uctypes
except ImportError:
print("SKIP missing uctypes")
else:
try:
ba = uctypes.bytearray_at(-9223372036854775808, 4) # -2**63
ba[0] = 1 # write to the mapped memory
print('should not reach here')
except Exception as e:
print("EXC %s" % type(e).__name__)
Expected behaviour
A Python-level exception instead of process crash, e.g.:
-
ValueError/OverflowError for negative address; or
-
OSError if the address is not accessible.
At minimum, uctypes.bytearray_at() should reject negative addresses on 64-bit builds rather than silently converting them to huge unsigned pointers.
Observed behaviour
Program received signal SIGSEGV, Segmentation fault.
#0 mp_binary_set_val_array_from_int(typecode=0x1, p=0x8000000000000000, index=0x0, val=0x1)
#1 mp_binary_set_val_array(...)
#2 array_subscr(...)
#3 mp_obj_subscr(...)
#4 mp_execute_bytecode(...)
Additional Information
No, I've provided everything above.
Code of Conduct
Yes, I agree