[PATCH, libgfortran] Add overflow check to xmalloc

[Bernhard Reutner-Fischer]

On 16 June 2014 08:20:09 Janne Blomqvist <blomqvist.janne@gmail.com> wrote:

> On Sun, Jun 15, 2014 at 8:23 AM, Bernhard Reutner-Fischer
> <rep.dot.nop@gmail.com> wrote:
> >
> >> >> 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?
> >> >>>
> >
> >
> > I would prefer if xcmalloc would not be named xmallocarray.
>
> Hmm, never heard of that one before, but I have no particular

Great, I fat-fingered it, meant xcalloc.

> preference wrt the naming of the function. Ok with that rename?
>
>
>
> --
> Janne Blomqvist



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