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

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

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On Tue, May 20, 2014 at 12:42 AM, Janne Blomqvist
<blomqvist.janne@gmail.com> wrote:
> 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



-- 
Janne Blomqvist