patch 9.0.2158: [security]: use-after-free in check_argument_type Commit: https://github.com/vim/vim/commit/0f28791b215bd4c22ed580839409c2f7d39d8140 Author: Christian Brabandt <cb@256bit.org> Date: Mon Dec 11 17:53:25 2023 +0100 patch 9.0.2158: [security]: use-after-free in check_argument_type Problem: [security]: use-after-free in check_argument_type Solution: Reset function type pointer when freeing the function type list function pointer fp->uf_func_type may point to the same memory, that was allocated for fp->uf_type_list. However, when cleaning up a function definition (e.g. because it was invalid), fp->uf_type_list will be freed, but fp->uf_func_type may still point to the same (now) invalid memory address. So when freeing the fp->uf_type_list, check if fp->func_type points to any of those types and if it does, reset the fp->uf_func_type pointer to the t_func_any (default) type pointer closes: #13652 Signed-off-by: Christian Brabandt <cb@256bit.org>

--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -2533,7 +2533,7 @@ func_clear_items(ufunc_T *fp)
     VIM_CLEAR(fp->uf_arg_types);
     VIM_CLEAR(fp->uf_block_ids);
     VIM_CLEAR(fp->uf_va_name);
-    clear_type_list(&fp->uf_type_list);
+    clear_func_type_list(&fp->uf_type_list, &fp->uf_func_type);
 
     // Increment the refcount of this function to avoid it being freed
     // recursively when the partial is freed.
@@ -5435,7 +5435,7 @@ errret_2:
     {
 	VIM_CLEAR(fp->uf_arg_types);
 	VIM_CLEAR(fp->uf_va_name);
-	clear_type_list(&fp->uf_type_list);
+	clear_func_type_list(&fp->uf_type_list, &fp->uf_func_type);
     }
     if (free_fp)
 	VIM_CLEAR(fp);