From 64066b9acd9f8cffdf4840f797748f938a13f2d6 Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Wed, 17 Nov 2021 18:22:56 +0000
Subject: [PATCH] patch 8.2.3612: using freed memory with regexp using a mark

Problem:    Using freed memory with regexp using a mark.
Solution:   Get the line again after getting the mark position.

Reference:https://github.com/vim/vim/commit/64066b9acd9f8cffdf4840f797748f938a13f2d6
---
 src/regexp.c                      | 2 +-
 src/regexp_nfa.c                  | 8 ++++++++
 src/testdir/test_regexp_latin.vim | 8 ++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/regexp.c b/src/regexp.c
index 112f753..2e94e5a 100644
--- a/src/regexp.c
+++ b/src/regexp.c
@@ -1092,7 +1092,7 @@ typedef struct {
     // The current match-position is stord in these variables:
     linenr_T	lnum;		// line number, relative to first line
     char_u	*line;		// start of current line
-    char_u	*input;		// current input, points into "regline"
+    char_u	*input;		// current input, points into "line"
 
     int	need_clear_subexpr;	// subexpressions still need to be cleared
 #ifdef FEAT_SYN_HL
diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index bc4a4b6..433523e 100644
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -6623,8 +6623,16 @@ nfa_regmatch(
 	    case NFA_MARK_GT:
 	    case NFA_MARK_LT:
 	      {
+                size_t	col = rex.input - rex.line;
 		pos_T	*pos = getmark_buf(rex.reg_buf, t->state->val, FALSE);
 
+		// Line may have been freed, get it again.
+		if (REG_MULTI)
+		{
+		    rex.line = reg_getline(rex.lnum);
+		    rex.input = rex.line + col;
+		}
+
 		// Compare the mark position to the match position.
 		result = (pos != NULL		     // mark doesn't exist
 			&& pos->lnum > 0    // mark isn't set in reg_buf
diff --git a/src/testdir/test_regexp_latin.vim b/src/testdir/test_regexp_latin.vim
index 7a4d98f..3168edc 100644
--- a/src/testdir/test_regexp_latin.vim
+++ b/src/testdir/test_regexp_latin.vim
@@ -141,3 +141,11 @@ func Test_pattern_compile_speed()
   call assert_inrange(0.01, 10.0, reltimefloat(reltime(start)))
   set spc=
 endfunc
+
+func Test_using_mark_position()
+  " this was using freed memory
+  new
+  norm O0
+  call assert_fails("s/\\%')", 'E486:')
+  bwipe!
+endfunc
-- 
2.23.0