vim-patch:9.0.2035: [security] use-after-free with wildmenu (#25687)

Problem:  [security] use-after-free with wildmenu
Solution: properly clean up the wildmenu when exiting

Fix wildchar/wildmenu/pum memory corruption with special wildchar's

Currently, using `wildchar=<Esc>` or `wildchar=<C-\>` can lead to a
memory corruption if using wildmenu+pum, or wrong states if only using
wildmenu. This is due to the code only using one single place inside the
cmdline process loop to perform wild menu clean up (by checking
`end_wildmenu`) but there are other odd situations where the loop could
have exited and we need a post-loop clean up just to be sure. If the
clean up was not done you would have a stale popup menu referring to
invalid memory, or if not using popup menu, incorrect status line (if
`laststatus=0`).

For example, if you hit `<Esc>` two times when it's wildchar, there's a
hard-coded behavior to exit command-line as a failsafe for user, and if
you hit `<C-\><C-\><C-N>` it will also exit command-line, but the clean
up code would not have hit because of specialized `<C-\>` handling.

Fix Ctrl-E / Ctrl-Y to not cancel/accept wildmenu if they are also
used for 'wildchar'/'wildcharm'. Currently they don't behave properly,
and also have potentially memory unsafe behavior as the logic is
currently not accounting for this situation and try to do both.
(Previous patch that addressed this: vim/vim#11677)

Also, correctly document Escape key behavior (double-hit it to escape)
in wildchar docs as it's previously undocumented.

In addition, block known invalid chars to be set in `wildchar` option,
such as Ctrl-C and `<CR>`. This is just to make it clear to the user
they shouldn't be set, and is not required for this bug fix.

closes: vim/vim#13361

https://github.com/vim/vim/commit/8f4fb007e4d472b09ff6bed9ffa485e0c3093699

Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>

3 files changed, 176 insertions, 3 deletions

diff --git a/test/functional/options/cursorbind_spec.lua b/test/functional/options/cursorbind_spec.lua
index 1a03ed099a..498206936a 100644
--- a/test/functional/options/cursorbind_spec.lua
+++ b/test/functional/options/cursorbind_spec.lua
@@ -8,6 +8,7 @@ local feed = helpers.feed
 before_each(clear)
 
 describe("'cursorbind'", function()
+  -- oldtest: Test_cursorline_cursorbind_horizontal_scroll()
   it("behaves consistently whether 'cursorline' is set or not vim-patch:8.2.4795", function()
     local screen = Screen.new(60, 8)
     screen:set_default_attr_ids({
diff --git a/test/functional/ui/popupmenu_spec.lua b/test/functional/ui/popupmenu_spec.lua
index bfa4b7f14e..6d5546e0aa 100644
--- a/test/functional/ui/popupmenu_spec.lua
+++ b/test/functional/ui/popupmenu_spec.lua
@@ -3768,13 +3768,16 @@ describe('builtin popupmenu', function()
         ]])
       end)
 
-      -- oldtest: Test_wildmenu_pum_clear_entries()
-      it('wildoptions=pum when using odd wildchar', function()
+      -- oldtest: Test_wildmenu_pum_odd_wildchar()
+      it('wildoptions=pum with odd wildchar', function()
         screen:try_resize(30, 10)
+        -- Test odd wildchar interactions with pum. Make sure they behave properly
+        -- and don't lead to memory corruption due to improperly cleaned up memory.
         exec([[
           set wildoptions=pum
           set wildchar=<C-E>
         ]])
+
         feed(':sign <C-E>')
         screen:expect([[
                                         |
@@ -3788,7 +3791,97 @@ describe('builtin popupmenu', function()
           {1:~    }{n: unplace        }{1:         }|
           :sign define^                  |
         ]])
-        assert_alive()
+
+        -- <C-E> being a wildchar takes priority over its original functionality
+        feed('<C-E>')
+        screen:expect([[
+                                        |
+          {1:~                             }|
+          {1:~                             }|
+          {1:~    }{n: define         }{1:         }|
+          {1:~    }{s: jump           }{1:         }|
+          {1:~    }{n: list           }{1:         }|
+          {1:~    }{n: place          }{1:         }|
+          {1:~    }{n: undefine       }{1:         }|
+          {1:~    }{n: unplace        }{1:         }|
+          :sign jump^                    |
+        ]])
+
+        feed('<Esc>')
+        screen:expect([[
+          ^                              |
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+                                        |
+        ]])
+
+        -- Escape key can be wildchar too. Double-<Esc> is hard-coded to escape
+        -- command-line, and we need to make sure to clean up properly.
+        command('set wildchar=<Esc>')
+        feed(':sign <Esc>')
+        screen:expect([[
+                                        |
+          {1:~                             }|
+          {1:~                             }|
+          {1:~    }{s: define         }{1:         }|
+          {1:~    }{n: jump           }{1:         }|
+          {1:~    }{n: list           }{1:         }|
+          {1:~    }{n: place          }{1:         }|
+          {1:~    }{n: undefine       }{1:         }|
+          {1:~    }{n: unplace        }{1:         }|
+          :sign define^                  |
+        ]])
+
+        feed('<Esc>')
+        screen:expect([[
+          ^                              |
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+                                        |
+        ]])
+
+        -- <C-\> can also be wildchar. <C-\><C-N> however will still escape cmdline
+        -- and we again need to make sure we clean up properly.
+        command([[set wildchar=<C-\>]])
+        feed([[:sign <C-\><C-\>]])
+        screen:expect([[
+                                        |
+          {1:~                             }|
+          {1:~                             }|
+          {1:~    }{s: define         }{1:         }|
+          {1:~    }{n: jump           }{1:         }|
+          {1:~    }{n: list           }{1:         }|
+          {1:~    }{n: place          }{1:         }|
+          {1:~    }{n: undefine       }{1:         }|
+          {1:~    }{n: unplace        }{1:         }|
+          :sign define^                  |
+        ]])
+
+        feed('<C-N>')
+        screen:expect([[
+          ^                              |
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+          {1:~                             }|
+                                        |
+        ]])
       end)
     end
 
diff --git a/test/functional/ui/wildmode_spec.lua b/test/functional/ui/wildmode_spec.lua
index 0355c57b5a..3201135b67 100644
--- a/test/functional/ui/wildmode_spec.lua
+++ b/test/functional/ui/wildmode_spec.lua
@@ -17,6 +17,85 @@ describe("'wildmenu'", function()
     screen:attach()
   end)
 
+  -- oldtest: Test_wildmenu_screendump()
+  it('works', function()
+    screen:set_default_attr_ids({
+      [0] = {bold = true, foreground = Screen.colors.Blue};  -- NonText
+      [1] = {foreground = Screen.colors.Black, background = Screen.colors.Yellow};  -- WildMenu
+      [2] = {bold = true, reverse = true};  -- StatusLine
+    })
+    -- Test simple wildmenu
+    feed(':sign <Tab>')
+    screen:expect{grid=[[
+                               |
+      {0:~                        }|
+      {0:~                        }|
+      {1:define}{2:  jump  list  >    }|
+      :sign define^             |
+    ]]}
+
+    feed('<Tab>')
+    screen:expect{grid=[[
+                               |
+      {0:~                        }|
+      {0:~                        }|
+      {2:define  }{1:jump}{2:  list  >    }|
+      :sign jump^               |
+    ]]}
+
+    feed('<Tab>')
+    screen:expect{grid=[[
+                               |
+      {0:~                        }|
+      {0:~                        }|
+      {2:define  jump  }{1:list}{2:  >    }|
+      :sign list^               |
+    ]]}
+
+    -- Looped back to the original value
+    feed('<Tab><Tab><Tab><Tab>')
+    screen:expect{grid=[[
+                               |
+      {0:~                        }|
+      {0:~                        }|
+      {2:define  jump  list  >    }|
+      :sign ^                   |
+    ]]}
+
+    -- Test that the wild menu is cleared properly
+    feed('<Space>')
+    screen:expect{grid=[[
+                               |
+      {0:~                        }|
+      {0:~                        }|
+      {0:~                        }|
+      :sign  ^                  |
+    ]]}
+
+    -- Test that a different wildchar still works
+    feed('<Esc>')
+    command('set wildchar=<Esc>')
+    feed(':sign <Esc>')
+    screen:expect{grid=[[
+                               |
+      {0:~                        }|
+      {0:~                        }|
+      {1:define}{2:  jump  list  >    }|
+      :sign define^             |
+    ]]}
+
+    -- Double-<Esc> is a hard-coded method to escape while wildchar=<Esc>. Make
+    -- sure clean up is properly done in edge case like this.
+    feed('<Esc>')
+    screen:expect{grid=[[
+      ^                         |
+      {0:~                        }|
+      {0:~                        }|
+      {0:~                        }|
+                               |
+    ]]}
+  end)
+
   it('C-E to cancel wildmenu completion restore original input', function()
     feed(':sign <tab>')
     screen:expect([[