Bug report

Bug description:

https://github.com/python/cpython/blob/main/Objects/complexobject.c#L150_Py_c_pow() contains:

at=atan2(a.imag,a.real);phase=at*b.real;if (b.imag!=0.0) {len /=exp(at*b.imag);

An oss-fuzz pycompiler fuzzer identified a problem compiling the code " 9J**33J**3" within the optimizer folding the constant by doing the math in place. We haven't been able to reproduce this ourselves - but code inspection reveals a potential problem:

Cexp(x) can return 0 in a couple of cases. Which would lead to the /= executing an undefined division by zero operation.

I believe the correct_Py_c_pow() code should look something like:

if (b.imag!=0.0) {doubletmp_exp=exp(at*b.imag);if (exp==0.0||errno==ERANGE) {// Detected as OverflowError by our caller.r.real=Py_HUGE_VAL;r.imag=Py_HUGE_VAL;returnr;            }len /=tmp_exp;

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-113841: fix possible undefined division by 0 in _Py_c_pow() #127211
• [3.13] gh-113841: fix possible undefined division by 0 in _Py_c_pow() (GH-127211) #127216
• [3.12] gh-113841: fix possible undefined division by 0 in _Py_c_pow() (GH-127211) (GH-127216) #127530