commit 17cf2cb1d226b0ba2401304242df7ddd3b6f1ff2
author David Benjamin <davidben@google.com> Tue Dec 13 01:07:13 2016 -0500
committer Adam Langley <agl@google.com> Wed Dec 21 20:34:47 2016 +0000
tree 3e6b6da76353a25cad1850c46668107690e8b245
parent 56cadc3daf9090d7536d92319f0c6e7a39bf7f4f

Work around language and compiler bug in memcpy, etc.

Most C standard library functions are undefined if passed NULL, even
when the corresponding length is zero. This gives them (and, in turn,
all functions which call them) surprising behavior on empty arrays.
Some compilers will miscompile code due to this rule. See also
https://www.imperialviolet.org/2016/06/26/nonnull.html

Add OPENSSL_memcpy, etc., wrappers which avoid this problem.

BUG=23

Change-Id: I95f42b23e92945af0e681264fffaf578e7f8465e
Reviewed-on: https://boringssl-review.googlesource.com/12928
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>

ssl/ssl_test.cc

diff --git a/ssl/ssl_test.cc b/ssl/ssl_test.cc
index 8ede63c..796c051 100644
--- a/ssl/ssl_test.cc
+++ b/ssl/ssl_test.cc
@@ -673,7 +673,7 @@
   }
   encoded.reset(encoded_raw);
   if (encoded_len != input.size() ||
-      memcmp(input.data(), encoded.get(), input.size()) != 0) {
+      OPENSSL_memcmp(input.data(), encoded.get(), input.size()) != 0) {
     fprintf(stderr, "SSL_SESSION_to_bytes did not round-trip\n");
     hexdump(stderr, "Before: ", input.data(), input.size());
     hexdump(stderr, "After:  ", encoded_raw, encoded_len);
@@ -711,7 +711,7 @@
     fprintf(stderr, "i2d_SSL_SESSION did not advance ptr correctly\n");
     return false;
   }
-  if (memcmp(input.data(), encoded.get(), input.size()) != 0) {
+  if (OPENSSL_memcmp(input.data(), encoded.get(), input.size()) != 0) {
     fprintf(stderr, "i2d_SSL_SESSION did not round-trip\n");
     return false;
   }
@@ -838,7 +838,7 @@
   if (session->tlsext_tick == nullptr) {
     return nullptr;
   }
-  memset(session->tlsext_tick, 'a', ticket_len);
+  OPENSSL_memset(session->tlsext_tick, 'a', ticket_len);
   session->tlsext_ticklen = ticket_len;
 
   // Fix up the timeout.
@@ -1030,8 +1030,8 @@
   }
 
   ret->session_id_length = SSL3_SSL_SESSION_ID_LENGTH;
-  memset(ret->session_id, 0, ret->session_id_length);
-  memcpy(ret->session_id, &number, sizeof(number));
+  OPENSSL_memset(ret->session_id, 0, ret->session_id_length);
+  OPENSSL_memcpy(ret->session_id, &number, sizeof(number));
   return ret;
 }
 
@@ -1442,7 +1442,7 @@
   }
   bssl::UniquePtr<uint8_t> free_s1(s1_bytes);
 
-  return s0_len == s1_len && memcmp(s0_bytes, s1_bytes, s0_len) == 0;
+  return s0_len == s1_len && OPENSSL_memcmp(s0_bytes, s1_bytes, s0_len) == 0;
 }
 
 static bool ExpectFDs(const SSL *ssl, int rfd, int wfd) {
@@ -1711,7 +1711,8 @@
     return false;
   }
 
-  if (memcmp(cert_sha256, session->peer_sha256, SHA256_DIGEST_LENGTH) != 0) {
+  if (OPENSSL_memcmp(cert_sha256, session->peer_sha256, SHA256_DIGEST_LENGTH) !=
+      0) {
     fprintf(stderr, "peer_sha256 did not match.\n");
     return false;
   }
@@ -1747,10 +1748,10 @@
     fprintf(stderr, "ClientHello for version %04x too short.\n", version);
     return false;
   }
-  memset(client_hello.data() + kRandomOffset, 0, SSL3_RANDOM_SIZE);
+  OPENSSL_memset(client_hello.data() + kRandomOffset, 0, SSL3_RANDOM_SIZE);
 
   if (client_hello.size() != expected_len ||
-      memcmp(client_hello.data(), expected, expected_len) != 0) {
+      OPENSSL_memcmp(client_hello.data(), expected, expected_len) != 0) {
     fprintf(stderr, "ClientHello for version %04x did not match:\n", version);
     fprintf(stderr, "Got:\n\t");
     for (size_t i = 0; i < client_hello.size(); i++) {
@@ -2097,9 +2098,9 @@
   static const uint8_t kZeros[16] = {0};
 
   if (encrypt) {
-    memcpy(key_name, kZeros, sizeof(kZeros));
+    OPENSSL_memcpy(key_name, kZeros, sizeof(kZeros));
     RAND_bytes(iv, 16);
-  } else if (memcmp(key_name, kZeros, 16) != 0) {
+  } else if (OPENSSL_memcmp(key_name, kZeros, 16) != 0) {
     return 0;
   }
 
@@ -2124,7 +2125,7 @@
 
 #if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
   // Fuzzer-mode tickets are unencrypted.
-  memcpy(plaintext.get(), ciphertext, len);
+  OPENSSL_memcpy(plaintext.get(), ciphertext, len);
 #else
   static const uint8_t kZeros[16] = {0};
   const uint8_t *iv = session->tlsext_tick + 16;