# Bug report ### Bug description: These were all found by UBSan in our CI (it just hasn't been complaining about them). They need to be individually checked, some may be false positives. ``` # Objects/object.c:97:5: runtime error: member access within null pointer of type 'PyThreadState' (aka 'struct _ts') null:Objects/object.c ``` In `test_memoryview`: ``` # Objects/memoryobject.c:3032:15: runtime error: load of value 2, which is not a valid value for type 'bool' bool:Objects/memoryobject.c ``` In `test_ctypes`: ``` # Modules/_ctypes/cfield.c:644:1: runtime error: left shift of 1 by 63 places cannot be represented in type 'int64_t' (aka 'long') shift-base:Modules/_ctypes/cfield.c # Modules/_ctypes/cfield.c:640:1: runtime error: signed integer overflow: -2147483648 - 1 cannot be represented in type 'int' signed-integer-overflow:Modules/_ctypes/cfield.c ``` In `test_zstd`: ``` # Modules/_zstd/decompressor.c:598:56: runtime error: applying non-zero offset 18446744073709551615 to null pointer pointer-overflow:Modules/_zstd/decompressor.c ``` ``` # Modules/_io/stringio.c:350:24: runtime error: addition of unsigned offset to 0x7fd01ec25850 overflowed to 0x7fd01ec2584c pointer-overflow:Modules/_io/stringio.c ``` ``` # Objects/bytesobject.c:1190:25: runtime error: applying zero offset to null pointer pointer-overflow:Objects/bytesobject.c ``` ### CPython versions tested on: CPython main branch ### Operating systems tested on: _No response_ <!-- gh-linked-prs --> ### Linked PRs * gh-151274 * gh-148168 * gh-153187 * gh-153204 * gh-153258 * gh-153644 * gh-153645 * gh-154912 * gh-154913 * gh-154915 * gh-154926 <!-- /gh-linked-prs -->