+++ This bug was initially created as a clone of Bug #233161 +++

Description of problem:

The ChangeLog states this:

2007-02-08 17:30 Christos Zoulas <christos>

        * fix integer underflow in file_printf which can lead to
          to exploitable heap overflow (Jean-Sebastien Guay-Lero)

Christos clarifies further:


The crux of the problem is here:

-               if ((buf = realloc(ms->o.buf, len + 1024)) == NULL) {
-                       file_oomem(ms, len + 1024);
+               size = (ms->o.size - ms->o.left) + len + 1024;
+               if ((buf = realloc(ms->o.buf, size)) == NULL) {

Instead of allocating len + 1024 bytes on top of the previous size,
before the fix we allocated just len + 1024 bytes. So if the buffer
was let's say 4K, and we printed a string of len < 3K in this pass,
then we effectively decreased the size of the string instead of
growing it because of the realloc().

christos

Version-Release number of selected component (if applicable):

file-3.* is not affected.
RHEL-3, RHEL-4, RHEL-5, FC-5, FC-6

How reproducible:

No reproducer available.