[GRASS5] [bug #2767] (grass) r.stats bug (due to recent G_store() fix?)

[Glynn Clements]

guest user via RT wrote:

> Trying to fix the new (at least recently discovered) bug
> in r.stats:
> 
> lib/gis/cats.c
> 
> int 
> G_set_raster_cats_title (char *title, struct Categories *pcats)
> {
>     if (title == NULL) title="";
>     pcats->title = G_store (title);     <- it crashes here
>     G_newlines_to_spaces (pcats->title);
>     G_strip (pcats->title);
>       return 0;
> }
> 
> For the crashing map title="" (so above if condition used).
> Reverting locally store.c (G_store() function) didn't help.

G_store() calls G_malloc() which calls malloc().

If a program crashes in either malloc (or calloc, realloc etc) or
free, it's usually because the heap has become corrupted, typically
because something wrote beyond the bounds of a dynamically-allocated
block, overwriting the header of either the current block or the one
after it.

IOW, the crash is just a symptom; the bug lies elsewhere.

Locating this kind of bug can be awkward, as there tend not to be any
detectable side-effects at the point when the memory is corrupted.

There are various tools which can be used, including the MALLOC_CHECK_
environment variable and mcheck/mprobe functions (see the libc Info
file for details), and third-party memory debugging libraries such as
Electric Fence.

-- 
Glynn Clements <glynn at gclements.plus.com>