[GHC] #10904: C finalizer may be called on re-used memory

[GHC]

#10904: C finalizer may be called on re-used memory
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        Reporter:  bherzog           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Runtime System    |                 Version:  7.4.1
      Resolution:                    |                Keywords:
Operating System:  Linux             |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Runtime crash     |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by simonmar):

 I looked at the code, and I think you're right, there does seem to be a
 possibility that the finalizer will run after the memory has been
 reclaimed.  As a workaround you can follow the suggestion you made, namely
 use `mallocBytes` and then `newForeignPtr`.

 I'll think about how this can be fixed.  It's tricky, and we already have
 too much overhead for C finalizers (things got a lot more complicated
 during the recent changes to ensure ordering for finalizers, I think
 that's when the bug may have crept in).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10904#comment:1>
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