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Undefined behavior in struct.unpack #96735
Description
Reproducer:
import struct
struct.unpack('!q', b'\xff\xff\xff\xff\xff\xff\xff\xff')Error:
Modules/_struct.c:842:15: runtime error: left shift of 72057594037927935 by 8 places cannot be represented in type 'long long int'Compiler options:
./configure -C --with-pydebug --with-address-sanitizer --with-undefined-behavior-sanitizer
Python version: Python 3.12.0a0 (heads/main:30cc1901efa, Sep 10 2022, 10:14:58) [GCC 9.4.0] on linux
Activity
kumaraditya303 commentedon Sep 10, 2022
cc @mdickinson
mdickinson commentedon Sep 10, 2022
@kumaraditya303 Thanks; this should be an easy fix.
gh-96735: Fix undefined behaviour in struct unpacking functions (#96739)
mdickinson commentedon Sep 25, 2022
Fixed for 3.12 in #96739. I agree with @matthiasgoergens that it's not worth fixing in 3.10 and 3.11, because the issue doesn't manifest itself in release builds, where
-fwrapvis used.