[Bug fortran/113793] New: malloc abort on character allocate with source argument

[Bug fortran/113793] New: malloc abort on character allocate with source argument

[manfred99 at gmx dot ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113793

            Bug ID: 113793
           Summary: malloc abort on character allocate with source
                    argument
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: manfred99 at gmx dot ch
  Target Milestone: ---

Allocating an allocatable character array, I get a malloc error
when the source argument is not properly padded:

      CHARACTER*30,allocatable :: a(:),b(:)
      ALLOCATE(a(100),source=" ")
      ALLOCATE(b(100),source=" ")
      END

yields:
malloc(): corrupted top size


When doing a lame indirection:
      CHARACTER*30,allocatable :: a(:),b(:)
      CHARACTER*30 :: c=" "
      ALLOCATE(a(100),source=c)
      ALLOCATE(b(100),source=c)
      END

everything is fine.
I don't know whether this is mandated by the standard, but the error
message is not very user friendly and hard to grasp.

I would have expected that the source argument is automatically padded
as with variable assignments and function call arguments.

[Bug fortran/113793] malloc abort on character allocate with source argument

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113793

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |anlauf at gcc dot gnu.org
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2024-02-07
           Keywords|                            |wrong-code
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from anlauf at gcc dot gnu.org ---
(In reply to Manfred Schwarb from comment #0)
> Allocating an allocatable character array, I get a malloc error
> when the source argument is not properly padded:
> 
>       CHARACTER*30,allocatable :: a(:),b(:)
>       ALLOCATE(a(100),source=" ")
>       ALLOCATE(b(100),source=" ")
>       END
> 
> yields:
> malloc(): corrupted top size

Confirmed.

> I would have expected that the source argument is automatically padded
> as with variable assignments and function call arguments.

The dump-tree shows that it is padded, but the actual malloc is too short:

            a.data = (void * restrict) __builtin_malloc (100);

Omitting the source= part, we get the expected:

            a.data = (void * restrict) __builtin_malloc (3000);

[Bug fortran/113793] malloc abort on character allocate with source argument

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113793

--- Comment #2 from anlauf at gcc dot gnu.org ---
Created attachment 57354
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57354&action=edit
Tentative partial patch

This appears to fix the malloc size for character arrays, but not for
allocatable scalars, like in:

program p
  implicit none
  CHARACTER*30,            allocatable :: a(:), b(:,:), d
  CHARACTER(kind=4,len=15),allocatable :: c(:), e
  ALLOCATE (a(100),source=" ")     ! OK
  ALLOCATE (b(5,6),source=" ")     ! OK
  ALLOCATE (c(42), source=4_"zzz") ! OK
  ALLOCATE (d,source="xx")         ! malloc too small
  ALLOCATE (e,source=4_"zz")       ! malloc too small
END

[Bug fortran/113793] malloc abort on character allocate with source argument

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113793

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #57354|0                           |1
        is obsolete|                            |

--- Comment #3 from anlauf at gcc dot gnu.org ---
Created attachment 57931
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57931&action=edit
Improved patch

This patch fixes both the scalar and the array variants.
Needs regtesting.

[Bug fortran/113793] malloc abort on character allocate with source argument

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113793

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #57931|0                           |1
        is obsolete|                            |

--- Comment #4 from anlauf at gcc dot gnu.org ---
Created attachment 57938
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57938&action=edit
Enhanced patch

This version add checks for standard conformance and a runtime check for
equal length.

[Bug fortran/113793] malloc abort on character allocate with source argument

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113793

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |accepts-invalid
           Priority|P3                          |P4

[Bug fortran/113793] malloc abort on character allocate with source argument

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113793

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |anlauf at gcc dot gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #5 from anlauf at gcc dot gnu.org ---
Submitted: https://gcc.gnu.org/pipermail/fortran/2024-April/060431.html

[Bug fortran/113793] malloc abort on character allocate with source argument

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113793

--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Harald Anlauf <anlauf@gcc.gnu.org>:

https://gcc.gnu.org/g:48024a99e3c2ae522d0026eedd591390506b68ca

commit r14-9996-g48024a99e3c2ae522d0026eedd591390506b68ca
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Sat Apr 13 19:09:24 2024 +0200

    Fortran: ALLOCATE of fixed-length CHARACTER with SOURCE/MOLD [PR113793]

    F2008 requires for ALLOCATE with SOURCE= or MOLD= specifier that the kind
    type parameters of allocate-object and source-expr have the same values.
    Add compile-time diagnostics for different character length and a runtime
    check (under -fcheck=bounds).  Use length from allocate-object to prevent
    heap corruption and to allow string padding or truncation on assignment.

    gcc/fortran/ChangeLog:

            PR fortran/113793
            * resolve.cc (resolve_allocate_expr): Reject ALLOCATE with SOURCE=
            or MOLD= specifier for unequal length.
            * trans-stmt.cc (gfc_trans_allocate): If an allocatable character
            variable has fixed length, use it and do not use the source length.
            With bounds-checking enabled, add a runtime check for same length.

    gcc/testsuite/ChangeLog:

            PR fortran/113793
            * gfortran.dg/allocate_with_source_29.f90: New test.
            * gfortran.dg/allocate_with_source_30.f90: New test.
            * gfortran.dg/allocate_with_source_31.f90: New test.

[Bug fortran/113793] malloc abort on character allocate with source argument

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113793

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |14.0
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #7 from anlauf at gcc dot gnu.org ---
Fixed on mainline for gcc-14.

Thanks for the report!