Re: [PATCH, libgfortran] Add overflow check to xmalloc

[Janne Blomqvist <blomqvist dot janne at gmail dot com>]

On Thu, May 15, 2014 at 1:00 AM, Janne Blomqvist
<blomqvist.janne@gmail.com> wrote:
> Hi,
>
> a common malloc() pattern is "malloc(num_foo * sizeof(foo_t)", that
> is, create space for an array of type foo_t with num_foo elements.
> There is a slight danger here in that the multiplication can overflow
> and wrap around, and then the caller thinks it has a larger array than
> what malloc has actually created. The attached patch changes the
> libgfortran xmalloc() function to have an API similar to calloc() with
> two arguments, and the implementation checks for wraparound.

Hello,

attached is an updated patch which instead introduces a new function,
xmallocarray, with the overflow check, and leaves the existing xmalloc
as is. Thus avoiding the extra checking in the common case where one
of the arguments to xmallocarray would be 1.

Tested on x86_64-unknown-linux-gnu, Ok for trunk?

2014-05-20  Janne Blomqvist  <jb@gcc.gnu.org>

    * libgfortran.h (xmallocarray): New prototype.
    * runtime/memory.c (xmallocarray): New function.
    (xcalloc): Check for nonzero separately instead of multiplying.
    * generated/*.c: Regenerated.
    * intrinsics/cshift0.c (cshift0): Call xmallocarray instead of
    xmalloc.
    * intrinsics/eoshift0.c (eoshift0): Likewise.
    * intrinsics/eoshift2.c (eoshift2): Likewise.
    * intrinsics/pack_generic.c (pack_internal): Likewise.
    (pack_s_internal): Likewise.
    * intrinsics/reshape_generic.c (reshape_internal): Likewise.
    * intrinsics/spread_generic.c (spread_internal): Likewise.
    (spread_internal_scalar): Likewise.
    * intrinsics/string_intrinsics_inc.c (string_trim): Likewise.
    (string_minmax): Likewise.
    * intrinsics/transpose_generic.c (transpose_internal): Likewise.
    * intrinsics/unpack_generic.c (unpack_internal): Likewise.
    * io/list_read.c (nml_touch_nodes): Don't cast xmalloc return value.
    * io/transfer.c (st_set_nml_var): Call xmallocarray instead of
    xmalloc.
    * io/unit.c (get_internal_unit): Likewise.
    (filename_from_unit): Don't cast xmalloc return value.
    * io/write.c (nml_write_obj): Likewise, formatting.
    * m4/bessel.m4 (bessel_jn_r'rtype_kind`): Call xmallocarray
    instead of xmalloc.
    (besse_yn_r'rtype_kind`): Likewise.
    * m4/cshift1.m4 (cshift1): Likewise.
    * m4/eoshift1.m4 (eoshift1): Likewise.
    * m4/eoshift3.m4 (eoshift3): Likewise.
    * m4/iforeach.m4: Likewise.
    * m4/ifunction.m4: Likewise.
    * m4/ifunction_logical.m4 (name`'rtype_qual`_'atype_code):
    Likewise.
    * m4/in_pack.m4 (internal_pack_'rtype_ccode`): Likewise.
    * m4/matmul.m4 (matmul_'rtype_code`): Likewise.
    * m4/matmull.m4 (matmul_'rtype_code`): Likewise.
    * m4/pack.m4 (pack_'rtype_code`): Likewise.
    * m4/reshape.m4 (reshape_'rtype_ccode`): Likewise.
    * m4/shape.m4 (shape_'rtype_kind`): Likewise.
    * m4/spread.m4 (spread_'rtype_code`): Likewise.
    (spread_scalar_'rtype_code`): Likewise.
    * m4/transpose.m4 (transpose_'rtype_code`): Likewise.
    * m4/unpack.m4 (unpack0_'rtype_code`): Likewise.
    (unpack1_'rtype_code`): Likewise.
    * runtime/convert_char.c (convert_char1_to_char4): Likewise.
    (convert_char4_to_char1): Simplify.
    * runtime/environ.c (init_unformatted): Call xmallocarray instead
    of xmalloc.
    * runtime/in_pack_generic.c (internal_pack): Likewise.




-- 
Janne Blomqvist

Attachment: xmalloc2.diff.gz
Description: GNU Zip compressed data