CVE request: ppthtml heap-based buffer overflow

[Murray McAllister <mmcallis () redhat com>]

Morning,

A heap-based buffer overflow flaw was reported in ppthtml:

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=729279

Looking in xlhtml-0.5-15.fc19.src.rpm, I think the root cause of the 
problem is in __OLEdecode() with an under allocation here:

163   BDepot = (U8 *) malloc (0x0200 * (num_bbd_blocks + num_xbbd_blocks));

That still passes this check:

167   assert (num_bbd_blocks <=  (0x0200 / 4 - 1) * num_xbbd_blocks +
168                              (0x0200 / 4) - 19);

I suspect the overflow eventually occurs in this loop:

184   for (i = 0; i < num_xbbd_blocks; i++)

with:

203       fread (s, 0x0200, 1, input);
204       test_exitf (!ferror (input), 5, ends ());
205       s += 0x0200;

continually executed (but haven't tested thoroughly!!!).

Can a CVE please be assigned?

(Cc'ing Salvatore in case there is more information in the Debian report 
that I cannot see.)

Cheers,

--
Murray McAllister / Red Hat Security Response Team