patch 8.2.3756: might crash when callback is not validv8.2.3756

Problem:    might crash when callback is not valid.
Solution:   Check for valid callback. (Yegappan Lakshmanan, closes #9293)

1 files changed, 2 insertions, 1 deletions

diff --git a/src/tag.c b/src/tag.c
index f932934769..41d21b7514 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -1361,7 +1361,8 @@ find_tagfunc_tags(
     dict_T	*d;
     taggy_T	*tag = &curwin->w_tagstack[curwin->w_tagstackidx];
 
-    if (*curbuf->b_p_tfu == NUL)
+    if (*curbuf->b_p_tfu == NUL || curbuf->b_tfu_cb.cb_name == NULL
+					   || *curbuf->b_tfu_cb.cb_name == NUL)
 	return FAIL;
 
     args[0].v_type = VAR_STRING;