Commit c8c258a4 authored by Nick Mathewson's avatar Nick Mathewson 🦀
Browse files

Merge branch 'bug24733_squashed_2'

parents ca1d1c38 519fa1a3

changes/bug24733

0 → 100644
+6 −0
Original line number Diff line number Diff line 
  o Minor bugfixes (code correctness):

    - Stop invoking undefined behaviour by using tor_free() on an unaligned

      pointer in get_interface_addresses_ioctl(). This pointer alignment issue

      exists on x86_64 macOS, but is unlikely to exist elsewhere.

      Fixes bug 24733; bugfix on 0.3.0.0-alpha-dev;

      not in any released version of tor.

src/common/address.c

+13 −1
Original line number Diff line number Diff line
@@ -1515,6 +1515,18 @@ get_interface_addresses_win32(int severity, sa_family_t family) 
#define _SIZEOF_ADDR_IFREQ sizeof

#endif



/* Free ifc->ifc_buf safely. */

static void

ifconf_free_ifc_buf(struct ifconf *ifc)

{

  /* On macOS, tor_free() takes the address of ifc.ifc_buf, which leads to

   * undefined behaviour, because pointer-to-pointers are expected to be

   * aligned at 8-bytes, but the ifconf structure is packed.  So we use

   * raw_free() instead. */

  raw_free(ifc->ifc_buf);

  ifc->ifc_buf = NULL;

}



/** Convert <b>*buf</b>, an ifreq structure array of size <b>buflen</b>,

 * into smartlist of <b>tor_addr_t</b> structures.

 */
@@ -1601,7 +1613,7 @@ get_interface_addresses_ioctl(int severity, sa_family_t family) 
 done:

  if (fd >= 0)

    close(fd);

  tor_free(ifc.ifc_buf);

  ifconf_free_ifc_buf(&ifc);

  return result;

}

#endif /* defined(HAVE_IFCONF_TO_SMARTLIST) */

src/common/util.h

+5 −0
Original line number Diff line number Diff line
@@ -79,6 +79,11 @@ extern int dmalloc_free(const char *file, const int line, void *pnt, 
 *

 * This is a macro.  If you need a function pointer to release memory from

 * tor_malloc(), use tor_free_().

 *

 * Note that this macro takes the address of the pointer it is going to

 * free and clear.  If that pointer is stored with a nonstandard

 * alignment (eg because of a "packed" pragma) it is not correct to use

 * tor_free().

 */

#ifdef __GNUC__

#define tor_free(p) STMT_BEGIN                                 \