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Fix potential stack overflow in overset initialisation #405

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Fix potential stack overflow in overset initialisation #405

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32 changes: 13 additions & 19 deletions src/overset/oversetUtilities.F90
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Original file line number Diff line number Diff line change
Expand Up @@ -1240,7 +1240,7 @@ subroutine addToFringeList(fringeList, n, fringe)
integer(kind=intType), intent(inout) :: n

! Working Paramters
integer(kind=intType) :: fSize
integer(kind=intType) :: fSize, i
type(fringeType), dimension(:), pointer :: tmpFringePtr
fSize = size(fringeList)

Expand All @@ -1255,8 +1255,14 @@ subroutine addToFringeList(fringeList, n, fringe)
! Allocate new space
allocate (fringeList(int(1.5 * fSize)))

! Copy exsitng values
fringeList(1:fSize) = tmpFringePtr(1:fSize)
! Copy values to new array. Note: we deliberately use an explicit loop here rather than whole-array
! assignment (`fringeList(1:fSize) = tmpFringePtr(1:fSize)`). Because fringeList and tmpFringePtr are both
! pointers, a whole-array copy forces the compiler to materialise a temporary array. Under -Ofast, `
! -fstack-arrays` is enabled which means this temporary array will be stack allocated. Depending on the size
! of the mesh, the fringe list can exceed the default stack size, leading to a stack overflow.
do i = 1, fSize
fringeList(i) = tmpFringePtr(i)
end do

! Free original memory
deallocate (tmpFringePtr)
Expand All @@ -1274,6 +1280,7 @@ subroutine addToFringeBuffer(intBuffer, realBuffer, n, fringe)

use constants
use block, only: fringeType
use utils, only: reallocateInteger2, reallocateReal2

implicit none

Expand All @@ -1285,29 +1292,16 @@ subroutine addToFringeBuffer(intBuffer, realBuffer, n, fringe)

! Working Paramters
integer(kind=intType) :: fSize
integer(kind=intType), dimension(:, :), pointer :: tmpInt
real(kind=realType), dimension(:, :), pointer :: tmpReal
fSize = size(intBuffer, 2)

! Increment n for next item
n = n + 1

if (n > fSize) then

! Pointers to existing data:
tmpInt => intBuffer
tmpReal => realBuffer

! Allocate new space
allocate (intBuffer(5, int(1.5 * fSize)))
allocate (realBuffer(4, int(1.5 * fSize)))

! Copy exsitng values
intBuffer(:, 1:fSize) = tmpInt(:, 1:fSize)
realBuffer(:, 1:fSize) = tmpReal(:, 1:fSize)

! Free original memory
deallocate (tmpInt, tmpReal)
! Increase the buffer sizes by 50%.
call reallocateInteger2(intBuffer, 5, int(1.5 * fSize), 5, fSize, .true.)
call reallocateReal2(realBuffer, 4, int(1.5 * fSize), 4, fSize, .true.)

end if

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