Tim: It is in the release branch https://bitbucket.org/petsc/petsc/commits/f79229c73db120b69d05e6d49c19f429e0... Thanks for reporting it. Hong Hong,

we are fine with that. Thanks! Volker

2018-04-18 17:32 GMT+02:00 Hong <[email protected]>:

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Tim :

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Hi all,

with PETSc v3.9 there seems to be a out of bounds write in the fortran interface of MatCreateSubmatrices.

https://bitbucket.org/petsc/petsc/src/59479656cffe26dd9a9d446f6d00df

e5e3168168/src/mat/interface/ftn-custom/zmatrixf.c?at= maint&fileviewer=file-view-default#zmatrixf.c-609

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The reference mentions that in fortran one should pass a preallocated array for submat with at least the size of m (actually it's probably a typo and should be n)

http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/

MatCreateSubMatrices.html

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Then n+1 entries are copied into that array, where the last entry seems to be some unneeded dummy (as mentioned). for (i=0; i<=*n; i++) { /* lsmat[*n] might be a dummy matrix for saving data struc */ smat[i] = lsmat[i]; } This leads to some bad errors afterwards, when that array is only of the size of n as recommended.

We need this extra space for reuse -- I agree it makes Fortran API odd.

I made following fix to the help manual: diff --git a/src/mat/interface/matrix.c b/src/mat/interface/matrix.c

When finished using the submatrices, the user should destroy - them with MatDestroyMatrices(). + them with MatDestroySubMatrices().

Fortran Note: The Fortran interface is slightly different from that given below; it - requires one to pass in as submat a Mat (integer) array of size at least m. + requires one to pass in as submat a Mat (integer) array of size at least n+1.

If you agree, I'll push it to the petsc released version.

Hong