merge revision(s) 55054: [Backport #12390]
* string.c (rb_str_modify_expand): check integer overflow. [ruby-core:75592] [Bug #12390]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@55426 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 55054: [Backport #12390]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@55426 b2dd03c8-39d4-4d8f-98ff-823fe69b080e