patch 9.0.0805: filetype autocmd may cause freed memory access

Problem:    Filetype autocmd may cause freed memory access.
Solution:   Set the quickfix-busy flag while filling the buffer.

src/quickfix.c

@@ -4595,6 +4595,9 @@ qf_update_buffer(qf_info_T *qi, qfline_T *old_last)
 	    qf_winid = win->w_id;
 	}
 
+	// autocommands may cause trouble
+	incr_quickfix_busy();
+
 	if (old_last == NULL)
 	    // set curwin/curbuf to buf and save a few things
 	    aucmd_prepbuf(&aco, buf);
@@ -4616,6 +4619,9 @@ qf_update_buffer(qf_info_T *qi, qfline_T *old_last)
 	// when the added lines are not visible.
 	if ((win = qf_find_win(qi)) != NULL && old_line_count < win->w_botline)
 	    redraw_buf_later(buf, UPD_NOT_VALID);
+
+	// always called after incr_quickfix_busy()
+	decr_quickfix_busy();
     }
 }
 

src/testdir/test_quickfix.vim

@@ -3455,6 +3455,21 @@ func Test_resize_from_copen()
   endtry
 endfunc
 
+func Test_filetype_autocmd()
+  " this changes the location list while it is in use to fill a buffer
+  lexpr ''
+  lopen
+  augroup FT_loclist
+    au FileType * call setloclist(0, [], 'f')
+  augroup END
+  silent! lolder
+  lexpr ''
+
+  augroup FT_loclist
+    au! FileType
+  augroup END
+endfunc
+
 func Test_vimgrep_with_textlock()
   new
 
@@ -6372,4 +6387,5 @@ func Test_info_line_with_space()
   call setqflist([], 'f')
 endfunc
 
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    805,
 /**/
     804,
 /**/