[dfsan] Wrap strcat

[morehouse]

compiler-rt/test/dfsan/custom.cpp

164

Doesn't this overtaint by 1 byte? sizeof() includes the null byte.

[stephan.yichao.zhao]

replaced sizeof+1 by sizeof

[stephan.yichao.zhao]

compiler-rt/test/dfsan/custom.cpp

164

Thank you. I confused sizeof and strlen.

[morehouse]

LGTM

compiler-rt/lib/dfsan/dfsan_custom.cpp

 void *__dfsw_memset(void *s, int c, size_t n,
                     dfsan_label s_label, dfsan_label c_label,
                     dfsan_label n_label, dfsan_label *ret_label) {
   dfsan_memset(s, c, c_label, n);
   *ret_label = s_label;
   return s;
 }
 
+SANITIZER_INTERFACE_ATTRIBUTE char *__dfsw_strcat(char *dest, const char *src,
+                                                  dfsan_label dest_label,
+                                                  dfsan_label src_label,
+                                                  dfsan_label *ret_label) {
+  size_t dest_len = strlen(dest);
+  char *ret = strcat(dest, src);
+  dfsan_label *sdest = shadow_for(dest + dest_len);
+  const dfsan_label *ssrc = shadow_for(src);
+  internal_memcpy((void *)sdest, (const void *)ssrc,
+                  strlen(src) * sizeof(dfsan_label));
+  *ret_label = dest_label;
+  return ret;
+}
+
 SANITIZER_INTERFACE_ATTRIBUTE char *
 __dfsw_strdup(const char *s, dfsan_label s_label, dfsan_label *ret_label) {
   size_t len = strlen(s);
   void *p = malloc(len+1);
   dfsan_memcpy(p, s, len+1);
   *ret_label = 0;
   return static_cast<char *>(p);
 }

compiler-rt/lib/dfsan/done_abilist.txt

 fun:strcpy=custom
 fun:strdup=custom
 fun:strncpy=custom
 fun:strtod=custom
 fun:strtol=custom
 fun:strtoll=custom
 fun:strtoul=custom
 fun:strtoull=custom
+fun:strcat=custom
 
 # Functions that produce an output that is computed from the input, but is not
 # necessarily data dependent.
 fun:bcmp=custom
 fun:memchr=custom
 fun:memcmp=custom
 fun:strcasecmp=custom
 fun:strchr=custom

compiler-rt/test/dfsan/custom.cpp

void test_strcmp() {
   assert(rv < 0);
 #ifdef STRICT_DATA_DEPENDENCIES
   ASSERT_ZERO_LABEL(rv);
 #else
   ASSERT_LABEL(rv, i_j_label);
 #endif
 }
 
+void test_strcat() {
+  char src[] = "world";
+  char dst[] = "hello \0    ";
+  char *p = dst;
+  dfsan_set_label(k_label, &p, sizeof(p));
+  dfsan_set_label(i_label, src, sizeof(src));
+  dfsan_set_label(j_label, dst, sizeof(dst));
+  char *ret = strcat(p, src);
+  ASSERT_LABEL(ret, k_label);
+  assert(ret == dst);
+  assert(strcmp(src, dst + 6) == 0);
+  for (int i = 0; i < 6; ++i) {
+    ASSERT_LABEL(dst[i], j_label);
+  }
+  for (int i = 6; i < strlen(dst); ++i) {
+    ASSERT_LABEL(dst[i], i_label);
+    assert(dfsan_get_label(dst[i]) == dfsan_get_label(src[i - 6]));
+  }
+  ASSERT_LABEL(dst[11], j_label);
+}
+
 void test_strlen() {
   char str1[] = "str1";
   dfsan_set_label(i_label, &str1[3], 1);
 
   int rv = strlen(str1);
   assert(rv == 4);
 #ifdef STRICT_DATA_DEPENDENCIES
   ASSERT_ZERO_LABEL(rv);
#endif
   test_sigemptyset();
   test_snprintf();
   test_socketpair();
   test_sprintf();
   test_stat();
   test_strcasecmp();
   test_strchr();
   test_strcmp();
+  test_strcat();
   test_strcpy();
   test_strdup();
   test_strlen();
   test_strncasecmp();
   test_strncmp();
   test_strncpy();
   test_strpbrk();
   test_strrchr();