bugfix(minor): handling of extremely large strings in dbgprintf() fixed

Previously, it could lead to garbagge output and, in extreme cases, also
to segfaults. Note: this was a problem only when debug output was
actually enabled, so it caused no problem in production use.

1 files changed, 9 insertions, 0 deletions

diff --git a/runtime/debug.c b/runtime/debug.c
index 4504aaad..bc581a5d 100644
--- a/runtime/debug.c
+++ b/runtime/debug.c
@@ -961,6 +961,15 @@ dbgprintf(char *fmt, ...)
 	va_start(ap, fmt);
 	lenWriteBuf = vsnprintf(pszWriteBuf, sizeof(pszWriteBuf), fmt, ap);
 	va_end(ap);
+	if(lenWriteBuf >= sizeof(pszWriteBuf)) {
+		/* prevent buffer overrruns and garbagge display */
+		pszWriteBuf[sizeof(pszWriteBuf) - 5] = '.';
+		pszWriteBuf[sizeof(pszWriteBuf) - 4] = '.';
+		pszWriteBuf[sizeof(pszWriteBuf) - 3] = '.';
+		pszWriteBuf[sizeof(pszWriteBuf) - 2] = '\n';
+		pszWriteBuf[sizeof(pszWriteBuf) - 1] = '\0';
+		lenWriteBuf = sizeof(pszWriteBuf);
+	}
 	dbgprint(NULL, pszWriteBuf, lenWriteBuf);
 }