[tor-commits] [tor/master] Wipe all of the target space in tor_addr_{to, from}_sockaddr()

[nickm at torproject.org]

commit d7ecdd645a68eeb7a5ab8c839479a05cc8a1e10e
Author: Nick Mathewson <nickm at torproject.org>
Date:   Mon Dec 29 10:06:12 2014 -0500

    Wipe all of the target space in tor_addr_{to,from}_sockaddr()
    
    Otherwise we risk a subsequent memdup or memcpy copying
    uninitialized RAM into some other place that might eventually expose
    it.  Let's make sure that doesn't happen.
    
    Closes ticket 14041
---
 changes/bug14041     |    5 +++++
 src/common/address.c |    7 +++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/changes/bug14041 b/changes/bug14041
new file mode 100644
index 0000000..d3d6538
--- /dev/null
+++ b/changes/bug14041
@@ -0,0 +1,5 @@
+  o Minor features (security):
+    - Clear all memory targetted by tor_addr_{to,from}_sockaddr(),
+      not just the part that's used. This makes it harder for data leak
+      bugs to occur in the event of other programming failures.
+      Resolves ticket 14041.
diff --git a/src/common/address.c b/src/common/address.c
index b2431ee..267b4e3 100644
--- a/src/common/address.c
+++ b/src/common/address.c
@@ -89,13 +89,14 @@ tor_addr_to_sockaddr(const tor_addr_t *a,
                      struct sockaddr *sa_out,
                      socklen_t len)
 {
+  memset(sa_out, 0, len);
+
   sa_family_t family = tor_addr_family(a);
   if (family == AF_INET) {
     struct sockaddr_in *sin;
     if (len < (int)sizeof(struct sockaddr_in))
       return 0;
     sin = (struct sockaddr_in *)sa_out;
-    memset(sin, 0, sizeof(struct sockaddr_in));
 #ifdef HAVE_STRUCT_SOCKADDR_IN_SIN_LEN
     sin->sin_len = sizeof(struct sockaddr_in);
 #endif
@@ -108,7 +109,6 @@ tor_addr_to_sockaddr(const tor_addr_t *a,
     if (len < (int)sizeof(struct sockaddr_in6))
       return 0;
     sin6 = (struct sockaddr_in6 *)sa_out;
-    memset(sin6, 0, sizeof(struct sockaddr_in6));
 #ifdef HAVE_STRUCT_SOCKADDR_IN6_SIN6_LEN
     sin6->sin6_len = sizeof(struct sockaddr_in6);
 #endif
@@ -129,6 +129,9 @@ tor_addr_from_sockaddr(tor_addr_t *a, const struct sockaddr *sa,
 {
   tor_assert(a);
   tor_assert(sa);
+
+  memset(a, 0, sizeof(*a));
+
   if (sa->sa_family == AF_INET) {
     struct sockaddr_in *sin = (struct sockaddr_in *) sa;
     tor_addr_from_ipv4n(a, sin->sin_addr.s_addr);