[AD] Electricfence positive with 4.0.3-rc2 stretch_blit

[Grzegorz Adam Hankiewicz <gradha@xxxxxxxxxx>]

Hi.

The attached program cores when I compile with "gcc -o a test.c -g
`allegro-config --static debug` -lefence -DDEBUGMODE=1".  The core
happens with both release and debug builds. Here's a backtrace from
a debug build:

(gdb) bt#0  0x40c17dc0 in ?? ()
#1  0x0807e2a3 in do_stretch_blit (source=0x40bfeca0, dest=0x40c11840, source_x=0, source_y=0, source_width=320,
    source_height=200, dest_x=0, dest_y=0, dest_width=640, dest_height=480, masked=0) at ./src/i386/istretch.c:423
#2  0x0807e3e0 in stretch_blit (s=0x40bfeca0, d=0x40c11840, s_x=0, s_y=0, s_w=320, s_h=200, d_x=0, d_y=0, d_w=640, d_h=480)
    at ./src/i386/istretch.c:447
#3  0x08058563 in _mangled_main () at test.c:13
#4  0x0807322f in main (argc=1, argv=0xbffffca4) at ./src/unix/umain.c:39
#5  0x4015914f in __libc_start_main () from /lib/libc.so.6
(gdb) f 1
#1  0x0807e2a3 in do_stretch_blit (source=0x40bfeca0, dest=0x40c11840, source_x=0, source_y=0, source_width=320,
    source_height=200, dest_x=0, dest_y=0, dest_width=640, dest_height=480, masked=0) at ./src/i386/istretch.c:423
423        _do_stretch(source, dest, _scratch_mem, sx>>16, sy, syd,
(gdb) list
418      #endif     /* ifdef GFX_MODEX */
419
420        COMPILER_RET();
421
422        /* call the stretcher */
423        _do_stretch(source, dest, _scratch_mem, sx>>16, sy, syd,
424                    dest_x, dest_y, dest_height, dest->vtable->color_depth);
425
426        /* and store it in the cache */
427        stretcher_info[best].sx = sx;
(gdb)

If I compile without electric fence, everything goes fine. Also,
exscale.c runs perfectly with and without electric fence. I'm
using electric-fence 2.1.13 and gcc 2.95.4. Can somebody duplicate
this apparently false positive?

#include <allegro.h>

int main(void)
{
   BITMAP *src, *bmp;

   ASSERT(!allegro_init());
   ASSERT(!install_timer());
   ASSERT(!install_keyboard());
   ASSERT(!set_gfx_mode(GFX_AUTODETECT, 640, 480, 640, 480));
   ASSERT(src = create_bitmap(320, 200));
   ASSERT(bmp = create_bitmap(640, 480));
   stretch_blit(src, bmp, 0, 0, src->w, src->h, 0, 0, bmp->w, bmp->h);
   readkey();
   return 0;
}
END_OF_MAIN();