[tor-commits] [tor/master] Use memset_s or explicit_bzero when available.

[nickm at torproject.org]

commit 3783046f3b519533fc721472f38ccf437d2d12a5
Author: Nick Mathewson <nickm at torproject.org>
Date:   Thu Jan 7 12:53:24 2016 -0800

    Use memset_s or explicit_bzero when available.
---
 changes/7419        |    7 +++++++
 configure.ac        |    2 ++
 src/common/crypto.c |    8 ++++++++
 3 files changed, 17 insertions(+)

diff --git a/changes/7419 b/changes/7419
new file mode 100644
index 0000000..b792e8f
--- /dev/null
+++ b/changes/7419
@@ -0,0 +1,7 @@
+  o Minor enhancement (security):
+    - Use explicit_bzero when present
+      from <logan at hackers.mu>.
+    - Use memset_s when present
+      from <selven at hackers.mu>
+
+    625538405474972d627b26d7a250ea36 (:
diff --git a/configure.ac b/configure.ac
index 7dfab58..b62b4d3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -381,6 +381,7 @@ AC_CHECK_FUNCS(
         backtrace_symbols_fd \
         clock_gettime \
 	eventfd \
+	explicit_bzero \
 	timingsafe_memcmp \
         flock \
         ftime \
@@ -399,6 +400,7 @@ AC_CHECK_FUNCS(
         localtime_r \
         lround \
         memmem \
+        memset_s \
 	pipe \
 	pipe2 \
         prctl \
diff --git a/src/common/crypto.c b/src/common/crypto.c
index bcb06e0..e62cc0a 100644
--- a/src/common/crypto.c
+++ b/src/common/crypto.c
@@ -2970,7 +2970,15 @@ memwipe(void *mem, uint8_t byte, size_t sz)
    * ...or maybe not.  In practice, there are pure-asm implementations of
    * OPENSSL_cleanse() on most platforms, which ought to do the job.
    **/
+
+#ifdef HAVE_EXPLICIT_BZERO
+  explicit_bzero(mem, sz);
+#elif HAVE_MEMSET_S
+  memset_s( mem, sz, 0, sz );
+#else
   OPENSSL_cleanse(mem, sz);
+#endif
+
   /* Just in case some caller of memwipe() is relying on getting a buffer
    * filled with a particular value, fill the buffer.
    *