From 060623e4a3bc72b011e7cd92bedb3bfb64e06200 Mon Sep 17 00:00:00 2001
From: Christian Brabandt <cb@256bit.org>
Date: Tue, 14 Nov 2023 21:33:29 +0100
Subject: [PATCH] patch 9.0.2110: [security]: overflow in ex address parsing

Problem:  [security]: overflow in ex address parsing
Solution: Verify that lnum is positive, before substracting from
          LONG_MAX

[security]: overflow in ex address parsing

When parsing relative ex addresses one may unintentionally cause an
overflow (because LONG_MAX - lnum will overflow for negative addresses).

So verify that lnum is actually positive before doing the overflow
check.

Signed-off-by: Christian Brabandt <cb@256bit.org>
---
 src/ex_docmd.c             | 2 +-
 src/testdir/test_excmd.vim | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 06837ac92c55c..01d411a632ccf 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -4644,7 +4644,7 @@ get_address(
 		    lnum -= n;
 		else
 		{
-		    if (n >= LONG_MAX - lnum)
+		    if (lnum >= 0 && n >= LONG_MAX - lnum)
 		    {
 			emsg(_(e_line_number_out_of_range));
 			goto error;
diff --git a/src/testdir/test_excmd.vim b/src/testdir/test_excmd.vim
index 3637351f636c0..47fc26726d5e6 100644
--- a/src/testdir/test_excmd.vim
+++ b/src/testdir/test_excmd.vim
@@ -724,5 +724,9 @@ func Test_write_after_rename()
   bwipe!
 endfunc
 
+" catch address lines overflow
+func Test_ex_address_range_overflow()
+  call assert_fails(':--+foobar', 'E492:')
+endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab