[ET Trac] [Einstein Toolkit] #1430: out-of-bounds write access checking in Cactus

[Einstein Toolkit]

#1430: out-of-bounds write access checking in Cactus
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 Reporter:  rhaas        |       Owner:                     
     Type:  enhancement  |      Status:  new                
 Priority:  minor        |   Milestone:                     
Component:  Other        |     Version:  development version
 Keywords:               |  
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 I possibly very useful (and simple to implement) debugging help in Cactus
 would be if the Cactus driver provided some means to detect array accesses
 out of the array/grid-function bounds. In general that is hard to do (in
 C, for Fortran there are compiler switches) however a possible useful
 partial solution might already be to put canary values before and after
 the user-visible data of grid functions/grid arrays. The flesh/driver
 could then check after each scheduled routine if any of the canary values
 were modified and if so output a warning.

 Schematically the layout in memory would be

   Canary1 data Canary2

 and CCTK_VarDataPtr would return a pointer to "data" only. After a
 scheduled function all we check Canary1 and Canary2 and output an error if
 they are corrupted. Similarly the
 IncreaseGroupStorage/DecreaseGroupStorage routines could set/check the
 canary values.

 This would prevent these errors triggering failures at some later
 unrelated call to malloc or free. glibc's malloc function provides some of
 this if _MALLOC_DEBUG is set, though I am not sure how well that actually
 works in practice in particular since eg OpenMP provides its own malloc
 function.

 I don't have an implementation of this right now and am mostly fishing for
 comments.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/1430>
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