From: Markus Koschany <apo@debian.org>
Date: Sun, 23 Oct 2022 17:18:10 +0200
Subject: CVE-2022-0351

Origin: https://github.com/vim/vim/commit/fe6fb267e6ee5c5da2f41889e4e0e0ac5bf4b89d
---
 src/eval.c                      | 10 ++++++++++
 src/testdir/test_eval_stuff.vim |  5 +++++
 2 files changed, 15 insertions(+)

diff --git a/src/eval.c b/src/eval.c
index 3f9db7d..00c73a6 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -4159,6 +4159,7 @@ eval7(
     char_u	*start_leader, *end_leader;
     int		ret = OK;
     char_u	*alias;
+    static	int recurse = 0;
 
     /*
      * Initialise variable so that clear_tv() can't mistake this for a
@@ -4174,6 +4175,14 @@ eval7(
 	*arg = skipwhite(*arg + 1);
     end_leader = *arg;
 
+    // Limit recursion to 1000 levels.  At least at 10000 we run out of stack
+    // and crash.
+    if (recurse == 1000)
+    {
+      return FAIL;
+    }
+    ++recurse;
+
     switch (**arg)
     {
     /*
@@ -4481,6 +4490,7 @@ eval7(
 	}
     }
 
+    --recurse;
     return ret;
 }
 
diff --git a/src/testdir/test_eval_stuff.vim b/src/testdir/test_eval_stuff.vim
index f4b3598..6c48c48 100644
--- a/src/testdir/test_eval_stuff.vim
+++ b/src/testdir/test_eval_stuff.vim
@@ -94,3 +94,8 @@ func Test_let_errmsg()
   call assert_fails('let v:errmsg = []', 'E730:')
   let v:errmsg = ''
 endfunc
+
+func Test_deep_recursion()
+  " this was running out of stack
+  call assert_fails("exe 'if ' . repeat('(', 1002)")
+endfunc