patch 9.0.2010: [security] use-after-free from buf_contents_changed()

Problem:  [security] use-after-free from buf_contents_changed()
Solution: block autocommands

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/buffer.c

@@ -6013,6 +6013,9 @@ buf_contents_changed(buf_T *buf)
 	return TRUE;
     }
 
+    // We don't want to trigger autocommands now, they may have nasty
+    // side-effects like wiping buffers
+    block_autocmds();
     if (ml_open(curbuf) == OK
 	    && readfile(buf->b_ffname, buf->b_fname,
 				  (linenr_T)0, (linenr_T)0, (linenr_T)MAXLNUM,
@@ -6038,6 +6041,8 @@ buf_contents_changed(buf_T *buf)
     if (curbuf != newbuf)	// safety check
 	wipe_buffer(newbuf, FALSE);
 
+    unblock_autocmds();
+
     return differ;
 }
 

src/testdir/test_crash.vim

@@ -78,6 +78,14 @@ func Test_crash1()
     \ '  && echo "crash 9: [OK]" >> X_crash1_result.txt' .. "\<cr>")
   call TermWait(buf, 1000)
 
+  let file = 'crash/editing_arg_idx_POC_1'
+  let args = printf(cmn_args, vim, file)
+  call term_sendkeys(buf, args ..
+    \ '  || echo "crash 10: [OK]" >> X_crash1_result.txt' .. "\<cr>")
+  call TermWait(buf, 1000)
+  call delete('Xerr')
+  call delete('@')
+
   " clean up
   exe buf .. "bw!"
 
@@ -93,6 +101,7 @@ func Test_crash1()
       \ 'crash 7: [OK]',
       \ 'crash 8: [OK]',
       \ 'crash 9: [OK]',
+      \ 'crash 10: [OK]',
       \ ]
 
   call assert_equal(expected, getline(1, '$'))

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2010,
 /**/
     2009,
 /**/