Revamp change_basename()

* Change the parameter from int to size_t.
  - Only caller doesn't need to change since it was already passing sizeof().
* Add unsigned wrapping checks.

2 files changed, 16 insertions, 7 deletions

diff --git a/lib/crypto/c_src/info.c b/lib/crypto/c_src/info.c
index 3f3194081d..d4e230dffd 100644
--- a/lib/crypto/c_src/info.c
+++ b/lib/crypto/c_src/info.c
@@ -30,21 +30,30 @@ char *crypto_callback_name = "crypto_callback.valgrind";
 char *crypto_callback_name = "crypto_callback";
 # endif
 
-int change_basename(ErlNifBinary* bin, char* buf, int bufsz, const char* newfile)
+int change_basename(ErlNifBinary* bin, char* buf, size_t bufsz, const char* newfile)
 {
-    int i;
+    size_t i;
+    size_t newlen;
 
     for (i = bin->size; i > 0; i--) {
 	if (bin->data[i-1] == '/')
 	    break;
     }
-    if (i + strlen(newfile) >= bufsz) {
-	PRINTF_ERR0("CRYPTO: lib name too long");
-	return 0;
-    }
+
+    newlen = strlen(newfile);
+    if (i > SIZE_MAX - newlen)
+        goto err;
+
+    if (i + newlen >= bufsz)
+        goto err;
+
     memcpy(buf, bin->data, i);
     strcpy(buf+i, newfile);
+
     return 1;
+
+ err:
+    return 0;
 }
 
 void error_handler(void* null, const char* errstr)
diff --git a/lib/crypto/c_src/info.h b/lib/crypto/c_src/info.h
index 4f8822ddd7..67690625c9 100644
--- a/lib/crypto/c_src/info.h
+++ b/lib/crypto/c_src/info.h
@@ -26,7 +26,7 @@
 #ifdef HAVE_DYNAMIC_CRYPTO_LIB
 extern char *crypto_callback_name;
 
-int change_basename(ErlNifBinary* bin, char* buf, int bufsz, const char* newfile);
+int change_basename(ErlNifBinary* bin, char* buf, size_t bufsz, const char* newfile);
 void error_handler(void* null, const char* errstr);
 #endif