[New-bugs-announce] [issue35959] math.prod(range(10)) caues segfault

[Karthikeyan Singaravelan]

New submission from Karthikeyan Singaravelan <tir.karthi at gmail.com>:

math.prod introduced with issue35606 seems to segfault when zero is present on some cases like start or middle of the iterable. I couldn't find the exact cause of this. This also occurs in optimized builds.

# Python information built with ./configure && make

➜  cpython git:(master) ./python.exe
Python 3.8.0a1+ (heads/master:8a03ff2ff4, Feb 11 2019, 00:13:49)
[Clang 7.0.2 (clang-700.1.81)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>

# Segfaults with range(10), [0, 1, 2, 3] and [1, 0, 2, 3]

➜  cpython git:(master) ./python.exe -X faulthandler -c 'import math; print(math.prod(range(10)))'
Fatal Python error: Floating point exception

Current thread 0x00007fff7939f300 (most recent call first):
  File "<string>", line 1 in <module>
[1]    40465 floating point exception  ./python.exe -X faulthandler -c 'import math; print(math.prod(range(10)))'

➜  cpython git:(master) ./python.exe -X faulthandler -c 'import math; print(math.prod([0, 1, 2, 3]))'
Fatal Python error: Floating point exception

Current thread 0x00007fff7939f300 (most recent call first):
  File "<string>", line 1 in <module>
[1]    40414 floating point exception  ./python.exe -X faulthandler -c 'import math; print(math.prod([0, 1, 2, 3]))'
➜  cpython git:(master) ./python.exe -X faulthandler -c 'import math; print(math.prod([1, 0, 2, 3]))'
Fatal Python error: Floating point exception

Current thread 0x00007fff7939f300 (most recent call first):
  File "<string>", line 1 in <module>
[1]    40425 floating point exception  ./python.exe -X faulthandler -c 'import math; print(math.prod([1, 0, 2, 3]))'


# No segfault when zero is at the end and floats seem to work fine.

➜  cpython git:(master) ./python.exe -X faulthandler -c 'import math; print(math.prod([1, 2, 3, 0]))'
0
➜  cpython git:(master) ./python.exe -c 'import math; print(math.prod(map(float, range(10))))'
0.0

----------
components: Library (Lib)
messages: 335168
nosy: pablogsal, rhettinger, xtreak
priority: normal
severity: normal
status: open
title: math.prod(range(10)) caues segfault
type: crash
versions: Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue35959>
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