merge revision(s) d5c33364e3c0efb15e11df417c925afee2cdb9c9: [Backport #16105]

	Fixed heap-use-after-free

	* string.c (rb_str_sub_bang): retrieves a pointer to the
	  replacement string buffer just before using it, for the case of
	  replacement with the receiver string itself.  [Bug #16105]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_6@67747 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 9 insertions, 2 deletions

diff --git a/string.c b/string.c
index 0caea99096..07268f0bb5 100644
--- a/string.c
+++ b/string.c
@@ -5078,7 +5078,7 @@ rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
                 cr = cr2;
 	}
 	plen = end0 - beg0;
-	rp = RSTRING_PTR(repl); rlen = RSTRING_LEN(repl);
+        rlen = RSTRING_LEN(repl);
 	len = RSTRING_LEN(str);
 	if (rlen > plen) {
 	    RESIZE_CAPA(str, len + rlen - plen);
@@ -5087,6 +5087,7 @@ rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
 	if (rlen != plen) {
 	    memmove(p + beg0 + rlen, p + beg0 + plen, len - beg0 - plen);
 	}
+	rp = RSTRING_PTR(repl);
 	memmove(p + beg0, rp, rlen);
 	len += rlen - plen;
 	STR_SET_LEN(str, len);
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index b8ae50d30d..23da909592 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -2008,6 +2008,12 @@ CODE
     r.taint
     a.sub!(/./, r)
     assert_predicate(a, :tainted?)
+
+    bug16105 = '[Bug #16105] heap-use-after-free'
+    a = S("ABCDEFGHIJKLMNOPQRSTUVWXYZ012345678")
+    b = a.dup
+    c = a.slice(1, 100)
+    assert_equal("AABCDEFGHIJKLMNOPQRSTUVWXYZ012345678", b.sub!(c, b), bug16105)
   end
 
   def test_succ
diff --git a/version.h b/version.h
index 5ea21f14f4..1b1ef96ea1 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.6.3"
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 97
+#define RUBY_PATCHLEVEL 98
 
 #define RUBY_RELEASE_YEAR 2019
 #define RUBY_RELEASE_MONTH 8