From: Vladimir Makarov <vmakarov@...>
Date: 2018-02-13T16:31:34-05:00
Subject: [ruby-core:85529] Re: [Ruby trunk Bug#14357] thread_safe tests suite segfaults

On 02/13/2018 05:13 AM, Eric Wong wrote:
> vmakarov@redhat.com wrote:
>> File thread-table-rebuild.patch added
> Thank you for working on this!
>
>>    This problem results in ICE for new hash tables.  For old hash
>> tables, the problem would have corrupted hash table structure which
>> probably results in later incorrect table behaviour.
> ICE - Internal Compiler Error?  Or did you mean "use-after-free"?
Fortunately, not internal compiler error (i wrongly used the term from 
GCC development :).  I meant use-after-free.
> Yes, 2.3 and earlier st.c is affected by this, too, just seems
> to hit less frequently...  2.3 maintainer(s) will need to
> backport from scratch, maybe
>
> <snip>
>
> I have no write access to Ruby repository. So please, consider the
<snip>
>> I cannot find where changelog entry should go for the current trunk,
>> but here it is.
> We write changelog entries in the commit message nowadays.  In the
> future, you can send the output of "git format-patch" since it
> appears you're using git anyways and we can "git am" it.
>
> I also wrote the following text to summarize in r62396
>
>      st.c: retry operations if rebuilt
>
>      Calling the .eql? and .hash methods during a Hash operation can
>      result in a thread switch or a signal handler to run: allowing
>      one execution context to rebuild the hash table while another is
>      still reading or writing the table.  This results in a
>      use-after-free bug affecting the thread_safe-0.3.6 test suite
>      and likely other bugs.
>
>      This bug did not affect users of commonly keys (String, Symbol,
>      Fixnum) as those are optimized to avoid method dispatch
>      for .eql? and .hash methods.
>
>      A separate version of this change needs to be ported to Ruby 2.3.x
>      which had a different implementation of st.c but was affected
>      by the same bug.
>
> (and copied your changelog entry below)
Thank you, Eric!


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