[issue35959] math.prod(range(10)) caues segfault

Mark Dickinson added the comment: I think this can be closed; I did look at the PR post-merge (sorry that I didn't get to it before it was merged), and I agree that it should fix the segfault. There's scope for refactoring / improving the implementation, but that would belong in a

[issue35959] math.prod(range(10)) caues segfault

Cheryl Sabella added the comment: Hi Pablo, Was this something you still wanted to clean up or can this be closed? Thanks! -- nosy: +cheryl.sabella ___ Python tracker ___

[issue35959] math.prod(range(10)) caues segfault

Pablo Galindo Salgado added the comment: @Mark long x = i_result * b; is still on the PR but the check for overflow does not use x. I will update the PR to move that line inside the overflow-safe block to prevent UB from happening and affecting the check itself (or the rest of the

[issue35959] math.prod(range(10)) caues segfault

Mark Dickinson added the comment: @Pablo: Thanks; I saw the PR. It looks as though the troublesome line long x = i_result * b; is still there in that PR, though. Or am I misreading? The difficulty here is that the check for overflow has to happen as a means of preventing invoking

[issue35959] math.prod(range(10)) caues segfault

Pablo Galindo Salgado added the comment: @Mark Dickinson Thanks for the links. I had opened yesterday PR11809 addressing the UB and adding more tests. Could you review the PR? -- ___ Python tracker

[issue35959] math.prod(range(10)) caues segfault

Karthikeyan Singaravelan added the comment: @pablogsal I am reopening this since this has an open PR though original issue was fixed. Feel free to close this if this can be discussed in a separate issue. -- resolution: fixed -> stage: resolved -> patch review status: closed -> open

[issue35959] math.prod(range(10)) caues segfault

Mark Dickinson added the comment: See below for a link to the Python 2.7 code for int * int multiplication (which needs to detect overflow so that it knows when to promote to long): https://github.com/python/cpython/blob/2f1a317d5fdc45b9d714b067906f612f636ba08e/Objects/intobject.c#L496-L518

[issue35959] math.prod(range(10)) caues segfault

Mark Dickinson added the comment: This approach to overflow checking needs reworking; the current code, in lines like: long x = i_result * b; induces undefined behaviour on overflow. That's something we need to avoid. -- nosy: +mark.dickinson

[issue35959] math.prod(range(10)) caues segfault

Change by Pablo Galindo Salgado : -- pull_requests: +11825, 11826, 11827 ___ Python tracker ___ ___ Python-bugs-list mailing list

[issue35959] math.prod(range(10)) caues segfault

Change by Pablo Galindo Salgado : -- pull_requests: +11825 ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue35959] math.prod(range(10)) caues segfault

Change by Pablo Galindo Salgado : -- pull_requests: +11825, 11826 ___ Python tracker ___ ___ Python-bugs-list mailing list

[issue35959] math.prod(range(10)) caues segfault

Change by Pablo Galindo Salgado : -- resolution: -> fixed stage: patch review -> resolved status: open -> closed ___ Python tracker ___

[issue35959] math.prod(range(10)) caues segfault

Pablo Galindo Salgado added the comment: PR11808 fixes the error and add some basic test. Please review the PR instead :) -- ___ Python tracker ___

[issue35959] math.prod(range(10)) caues segfault

Change by Pablo Galindo Salgado : -- keywords: +patch, patch, patch pull_requests: +11822, 11823, 11824 stage: -> patch review ___ Python tracker ___

[issue35959] math.prod(range(10)) caues segfault

Change by Pablo Galindo Salgado : -- keywords: +patch, patch pull_requests: +11822, 11823 stage: -> patch review ___ Python tracker ___

[issue35959] math.prod(range(10)) caues segfault

Change by Pablo Galindo Salgado : -- keywords: +patch pull_requests: +11822 stage: -> patch review ___ Python tracker ___ ___

[issue35959] math.prod(range(10)) caues segfault

Rémi Lapeyre added the comment: Could it be https://github.com/python/cpython/blob/master/Modules/mathmodule.c#L2565 When 0 is in the iterator, i_result get sets to 0 and then on the next iteration x/i_result is 0/0 which is undefined behavior? C99 6.5.5p5 - The result of the / operator is

[issue35959] math.prod(range(10)) caues segfault

Pablo Galindo Salgado added the comment: The problem is that the intermediate result (i_result) can be 0 when doing the overflow check: x / i_result != b i am working on a fix. -- ___ Python tracker

[issue35959] math.prod(range(10)) caues segfault

New submission from Karthikeyan Singaravelan : 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