commit f71bbd20a40de78fc1e7d722ba591578f137abec Author: Nick Mathewson nickm@torproject.org Date: Wed Jan 10 09:51:45 2018 -0500
Extract the raw_free() of ifc_buf into a new function.
Explain the problem more correctly. --- src/common/address.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/src/common/address.c b/src/common/address.c index ea14e6392..d96ec514b 100644 --- a/src/common/address.c +++ b/src/common/address.c @@ -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. */ @@ -1601,11 +1613,7 @@ get_interface_addresses_ioctl(int severity, sa_family_t family) done: if (fd >= 0) close(fd); - /* On macOS, tor_free() loads ifc.ifc_buf, which leads to undefined - * behaviour, because it is always aligned at 8-bytes (ifc) plus 4 bytes - * (ifc_len and pragma pack(4)). So we use raw_free() instead. */ - raw_free(ifc.ifc_buf); - ifc.ifc_buf = NULL; + ifconf_free_ifc_buf(&ifc); return result; } #endif /* defined(HAVE_IFCONF_TO_SMARTLIST) */