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[perl #118059] race condition+fail in dist\IO\t\cachepropagate-tcp.t

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From:
bulk88 via RT
Date:
September 20, 2013 08:15
Subject:
[perl #118059] race condition+fail in dist\IO\t\cachepropagate-tcp.t
Message ID:
rt-3.6.HEAD-1873-1379664891-1079.118059-15-0@perl.org
On Wed Aug 28 18:09:32 2013, tonyc wrote:
> 
> The output from a failed run looked like:
> 
> 1..8
> ok 1 - socket created
> ok 2 - protocol defined
> ok 3 - domain defined
> ok 4 - type defined
> ok 5 - spawned a child
> accept(3 (112)) => 236 but osfhandle returned bad -1
> Can't use an undefined value as a symbol reference at
> ../dist/IO/t/cachepropagate-tcp.t line 49.
> # Looks like you planned 8 tests but ran 5.
> # Looks like your test exited with 9 just after 5.
> 
> So it seems some race is closing the accept()ed socket before we get to
> use it.
> 
> Pretty much any output I do in the child or parent before the accept()
> prevents the problem from occuring for me, which makes it difficult to
test.
> 
> Tony

Using freeze/thaw features of the parent and child OS threads, the bug
can be prevented.  2 theories I have

1. somewhere a CloseHandle was done on a socket handle, which isn't
allowed on paper, because supposedly there are winsock user-mode
resources which aren't cleaned up when the kernel handle (a socket on NT
is a kernel handle from the AFD driver, IDK if its true that the AFD
driver won't cleanup/do a callback to the usermode winsock side when the
kernel handle is closed) is closed.

2. a double free (using the correct closesocket() command) was done,
when the child psuedo proc exited

I include 2 screen shots of why I think the above. The break happened at
a invalid handle exception from zwclose/ntclose. Notice it came from the
usermode winsock dll.

-- 
bulk88 ~ bulk88 at hotmail.com

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https://rt.perl.org:443/rt3/Ticket/Display.html?id=118059

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