From 6bf131888a3d1de62bbfa8a7ea03c0ddccfd496e Mon Sep 17 00:00:00 2001
From: Christian Brabandt <cb@256bit.org>
Date: Tue, 14 Nov 2023 22:42:59 +0100
Subject: [PATCH] patch 9.0.2112: [security]: overflow in shift_line

Problem:  [security]: overflow in shift_line
Solution: allow a max indent of INT_MAX

[security]: overflow in shift_line

When shifting lines in operator pending mode and using a very large
value, we may overflow the size of integer. Fix this by using a long
variable, testing if the result would be larger than INT_MAX and if so,
indent by INT_MAX value.

Special case: We cannot use long here, since on 32bit architectures (or
on Windows?), it typically cannot take larger values than a plain int,
so we have to use long long count, decide whether the resulting
multiplication of the shiftwidth value * amount is larger than INT_MAX
and if so, we will store INT_MAX as possible larges value in the long
long count variable.

Then we can safely cast it back to int when calling the functions to set
the indent (set_indent() or change_indent()). So this should be safe.

Add a test that when using a huge value in operator pending mode for
shifting, we will shift by INT_MAX

closes: #13535

Signed-off-by: Christian Brabandt <cb@256bit.org>
---
 src/ops.c                   | 15 ++++++++++-----
 src/testdir/test_indent.vim | 11 +++++++++++
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/src/ops.c b/src/ops.c
index c0a2981d68770..ecd7fc2170c58 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -229,11 +229,11 @@ shift_line(
     int	amount,
     int call_changed_bytes)	// call changed_bytes()
 {
-    int		count;
+    long long	count;
     int		i, j;
     int		sw_val = (int)get_sw_value_indent(curbuf);
 
-    count = get_indent();	// get current indent
+    count = (long long)get_indent();	// get current indent
 
     if (round)			// round off indent
     {
@@ -260,14 +260,19 @@ shift_line(
 		count = 0;
 	}
 	else
-	    count += sw_val * amount;
+	{
+	    if ((long long)sw_val * (long long)amount > INT_MAX - count)
+		count = INT_MAX;
+	    else
+		count += (long long)sw_val * (long long)amount;
+	}
     }
 
     // Set new indent
     if (State & VREPLACE_FLAG)
-	change_indent(INDENT_SET, count, FALSE, NUL, call_changed_bytes);
+	change_indent(INDENT_SET, (int)count, FALSE, NUL, call_changed_bytes);
     else
-	(void)set_indent(count, call_changed_bytes ? SIN_CHANGED : 0);
+	(void)set_indent((int)count, call_changed_bytes ? SIN_CHANGED : 0);
 }
 
 /*
diff --git a/src/testdir/test_indent.vim b/src/testdir/test_indent.vim
index 96e9d2300883c..217a7ae625072 100644
--- a/src/testdir/test_indent.vim
+++ b/src/testdir/test_indent.vim
@@ -275,4 +275,15 @@ func Test_formatting_keeps_first_line_indent()
   bwipe!
 endfunc
 
+" Test for indenting with large amount, causes overflow
+func Test_indent_overflow_count()
+  new
+  setl sw=8
+  call setline(1, "abc")
+  norm! V2147483647>
+  " indents by INT_MAX
+  call assert_equal(2147483647, indent(1))
+  close!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab