coretext: fix NULL CFStringRef dereference

diff --git a/libass/ass_coretext.c b/libass/ass_coretext.c
index d749df0e57142bebbc7b85ea7c08c519da918be9..aed4b02e87984c0534f1df67bdb58332ca799485 100644 (file)
--- a/libass/ass_coretext.c
+++ b/libass/ass_coretext.c
@@ -34,6 +34,8 @@ static const ASS_FontMapping font_substitutions[] = {
 
 static char *cfstr2buf(CFStringRef string)
 {
+    if (!string)
+        return NULL;
     const int encoding = kCFStringEncodingUTF8;
     const char *buf_ptr = CFStringGetCStringPtr(string, encoding);
     if (buf_ptr) {