vim: fix 2021-3796

vim is vulnerable to Use After Free
Problem: Checking first character of url twice.

reference:
https://github.com/vim/vim/commit/35a9a00afcb20897d462a766793ff45534810dc3

Signed-off-by: Minjae Kim <flowergom@gmail.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

diff --git a/meta/recipes-support/vim/files/CVE-2021-3796.patch b/meta/recipes-support/vim/files/CVE-2021-3796.patch
new file mode 100644 (file)
index 0000000..666bd5c
--- /dev/null
+++ b/meta/recipes-support/vim/files/CVE-2021-3796.patch
@@ -0,0 +1,50 @@
+From 6d02e1429771c00046b48f26e53ca4123c3ce4e1 Mon Sep 17 00:00:00 2001
+From: Bram Moolenaar <Bram@vim.org>
+Date: Fri, 24 Sep 2021 16:01:09 +0800
+Subject: [PATCH] patch 8.2.3428: using freed memory when replacing
+
+Problem:    Using freed memory when replacing. (Dhiraj Mishra)
+Solution:   Get the line pointer after calling ins_copychar().
+
+Upstream-Status: Backport [https://github.com/vim/vim/commit/35a9a00afcb20897d462a766793ff45534810dc3]
+CVE: CVE-2021-3796
+
+Signed-off-by: Minjae Kim  <flowergom@gmail.com>
+---
+ src/normal.c | 10 +++++++---
+ 1 file changed, 7 insertions(+), 3 deletions(-)
+
+diff --git a/src/normal.c b/src/normal.c
+index c4963e621..305b514bc 100644
+--- a/src/normal.c
++++ b/src/normal.c
+@@ -5009,19 +5009,23 @@ nv_replace(cmdarg_T *cap)
+           {
+               /*
+                * Get ptr again, because u_save and/or showmatch() will have
+-               * released the line.  At the same time we let know that the
+-               * line will be changed.
++               * released the line. This may also happen in ins_copychar().
++               * At the same time we let know that the line will be changed.
+                */
+-              ptr = ml_get_buf(curbuf, curwin->w_cursor.lnum, TRUE);
+               if (cap->nchar == Ctrl_E || cap->nchar == Ctrl_Y)
+               {
+                 int c = ins_copychar(curwin->w_cursor.lnum
+                                          + (cap->nchar == Ctrl_Y ? -1 : 1));
++
++                ptr = ml_get_buf(curbuf, curwin->w_cursor.lnum, TRUE);
+                 if (c != NUL)
+                   ptr[curwin->w_cursor.col] = c;
+               }
+               else
++              {
++                  ptr = ml_get_buf(curbuf, curwin->w_cursor.lnum, TRUE);
+                   ptr[curwin->w_cursor.col] = cap->nchar;
++              }
+               if (p_sm && msg_silent == 0)
+                   showmatch(cap->nchar);
+               ++curwin->w_cursor.col;
+-- 
+2.17.1
+