diff options
author | usa <usa@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2019-08-26 15:58:57 +0000 |
---|---|---|
committer | usa <usa@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2019-08-26 15:58:57 +0000 |
commit | 689a6a0a763517e5fa1fc078b2f8130e0af7c4c0 (patch) | |
tree | 9181ab2b259aa775f5e366b3988a8eb2b8401883 | |
parent | 470dae33ea1a958bb00739b083c1c582a8f16e10 (diff) |
merge revision(s) 3f9562015e651735bfc2fdd14e8f6963b673e22a,c06ddfee878524168e4af07443217ed2f8d0954b,3b3b4a44e5: [Backport #15792]
Get rid of indirect sharing
* string.c (str_duplicate): share the root shared string if the
original string is already sharing, so that all shared strings
refer the root shared string directly. indirect sharing can
cause a dangling pointer.
[Bug #15792]
str_duplicate: Don't share with a frozen shared string
This is a follow up for 3f9562015e651735bfc2fdd14e8f6963b673e22a.
Before this commit, it was possible to create a shared string which
shares with another shared string by passing a frozen shared string
to `str_duplicate`.
Such string looks like:
```
-------- -----------------
| root | ------ owns -----> | root's buffer |
-------- -----------------
^ ^ ^
----------- | |
| shared1 | ------ references ----- |
----------- |
^ |
----------- |
| shared2 | ------ references ---------
-----------
```
This is bad news because `rb_fstring(shared2)` can make `shared1`
independent, which severs the reference from `shared1` to `root`:
```c
/* from fstr_update_callback() */
str = str_new_frozen(rb_cString, shared2); /* can return shared1 */
if (STR_SHARED_P(str)) { /* shared1 is also a shared string */
str_make_independent(str); /* no frozen check */
}
```
If `shared1` was the only reference to `root`, then `root` can be
reclaimed by the GC, leaving `shared2` in a corrupted state:
```
----------- --------------------
| shared1 | -------- owns --------> | shared1's buffer |
----------- --------------------
^
|
----------- -------------------------
| shared2 | ------ references ----> | root's buffer (freed) |
----------- -------------------------
```
Here is a reproduction script for the situation this commit fixes.
```ruby
a = ('a' * 24).strip.freeze.strip
-a
p a
4.times { GC.start }
p a
```
- string.c (str_duplicate): always share with the root string when
the original is a shared string.
- test_rb_str_dup.rb: specifically test `rb_str_dup` to make
sure it does not try to share with a shared string.
[Bug #15792]
Closes: https://github.com/ruby/ruby/pull/2159
Update dependencies
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@67766 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
-rw-r--r-- | ext/-test-/string/depend | 11 | ||||
-rw-r--r-- | ext/-test-/string/rb_str_dup.c | 35 | ||||
-rw-r--r-- | string.c | 11 | ||||
-rw-r--r-- | test/-ext-/string/test_rb_str_dup.rb | 16 | ||||
-rw-r--r-- | test/ruby/test_string.rb | 9 | ||||
-rw-r--r-- | version.h | 2 |
6 files changed, 79 insertions, 5 deletions
diff --git a/ext/-test-/string/depend b/ext/-test-/string/depend index 8e7ee2a55a..71e995a523 100644 --- a/ext/-test-/string/depend +++ b/ext/-test-/string/depend @@ -173,6 +173,17 @@ qsort.o: $(hdrdir)/ruby/subst.h qsort.o: $(hdrdir)/ruby/util.h qsort.o: $(top_srcdir)/include/ruby.h qsort.o: qsort.c +rb_str_dup.o: $(RUBY_EXTCONF_H) +rb_str_dup.o: $(arch_hdrdir)/ruby/config.h +rb_str_dup.o: $(hdrdir)/ruby.h +rb_str_dup.o: $(hdrdir)/ruby/backward.h +rb_str_dup.o: $(hdrdir)/ruby/defines.h +rb_str_dup.o: $(hdrdir)/ruby/intern.h +rb_str_dup.o: $(hdrdir)/ruby/missing.h +rb_str_dup.o: $(hdrdir)/ruby/ruby.h +rb_str_dup.o: $(hdrdir)/ruby/st.h +rb_str_dup.o: $(hdrdir)/ruby/subst.h +rb_str_dup.o: rb_str_dup.c set_len.o: $(RUBY_EXTCONF_H) set_len.o: $(arch_hdrdir)/ruby/config.h set_len.o: $(hdrdir)/ruby/backward.h diff --git a/ext/-test-/string/rb_str_dup.c b/ext/-test-/string/rb_str_dup.c new file mode 100644 index 0000000000..a0bd65820f --- /dev/null +++ b/ext/-test-/string/rb_str_dup.c @@ -0,0 +1,35 @@ +#include "ruby.h" + +VALUE rb_str_dup(VALUE str); + +static VALUE +bug_rb_str_dup(VALUE self, VALUE str) +{ + rb_check_type(str, T_STRING); + return rb_str_dup(str); +} + +static VALUE +bug_shared_string_p(VALUE self, VALUE str) +{ + rb_check_type(str, T_STRING); + return RB_FL_TEST(str, RUBY_ELTS_SHARED) && RB_FL_TEST(str, RSTRING_NOEMBED) ? Qtrue : Qfalse; +} + +static VALUE +bug_sharing_with_shared_p(VALUE self, VALUE str) +{ + rb_check_type(str, T_STRING); + if (bug_shared_string_p(self, str)) { + return bug_shared_string_p(self, RSTRING(str)->as.heap.aux.shared); + } + return Qfalse; +} + +void +Init_string_rb_str_dup(VALUE klass) +{ + rb_define_singleton_method(klass, "rb_str_dup", bug_rb_str_dup, 1); + rb_define_singleton_method(klass, "shared_string?", bug_shared_string_p, 1); + rb_define_singleton_method(klass, "sharing_with_shared?", bug_sharing_with_shared_p, 1); +} @@ -1472,10 +1472,13 @@ str_duplicate(VALUE klass, VALUE str) MEMCPY(RSTRING(dup)->as.ary, RSTRING(str)->as.ary, char, embed_size); if (flags & STR_NOEMBED) { - if (UNLIKELY(!(flags & FL_FREEZE))) { - str = str_new_frozen(klass, str); - FL_SET_RAW(str, flags & FL_TAINT); - flags = FL_TEST_RAW(str, flag_mask); + if (FL_TEST_RAW(str, STR_SHARED)) { + str = RSTRING(str)->as.heap.aux.shared; + } + else if (UNLIKELY(!(flags & FL_FREEZE))) { + str = str_new_frozen(klass, str); + FL_SET_RAW(str, flags & FL_TAINT); + flags = FL_TEST_RAW(str, flag_mask); } if (flags & STR_NOEMBED) { RB_OBJ_WRITE(dup, &RSTRING(dup)->as.heap.aux.shared, str); diff --git a/test/-ext-/string/test_rb_str_dup.rb b/test/-ext-/string/test_rb_str_dup.rb new file mode 100644 index 0000000000..49b6af9598 --- /dev/null +++ b/test/-ext-/string/test_rb_str_dup.rb @@ -0,0 +1,16 @@ +require 'test/unit' +require '-test-/string' + +class Test_RbStrDup < Test::Unit::TestCase + def test_nested_shared_non_frozen + str = Bug::String.rb_str_dup(Bug::String.rb_str_dup("a" * 50)) + assert_send([Bug::String, :shared_string?, str]) + assert_not_send([Bug::String, :sharing_with_shared?, str], '[Bug #15792]') + end + + def test_nested_shared_frozen + str = Bug::String.rb_str_dup(Bug::String.rb_str_dup("a" * 50).freeze) + assert_send([Bug::String, :shared_string?, str]) + assert_not_send([Bug::String, :sharing_with_shared?, str], '[Bug #15792]') + end +end diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb index c0c4fe451a..d4303e87c1 100644 --- a/test/ruby/test_string.rb +++ b/test/ruby/test_string.rb @@ -2921,6 +2921,15 @@ CODE end =end + def test_nesting_shared + a = ('a' * 24).encode(Encoding::ASCII).gsub('x', '') + hash = {} + hash[a] = true + assert_equal(('a' * 24), a) + 4.times { GC.start } + assert_equal(('a' * 24), a, '[Bug #15792]') + end + def test_shared_force_encoding s = "\u{3066}\u{3059}\u{3068}".gsub(//, '') h = {} @@ -1,6 +1,6 @@ #define RUBY_VERSION "2.5.6" #define RUBY_RELEASE_DATE "2019-08-27" -#define RUBY_PATCHLEVEL 184 +#define RUBY_PATCHLEVEL 185 #define RUBY_RELEASE_YEAR 2019 #define RUBY_RELEASE_MONTH 8 |