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author | Alan Wu <XrXr@users.noreply.github.com> | 2019-09-22 15:36:00 -0400 |
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committer | Nobuyoshi Nakada <nobu@ruby-lang.org> | 2019-09-26 15:30:18 +0900 |
commit | 93faa011d393bb4b5cf31a0cbb46922f0a5e7cdc (patch) | |
tree | 1e1d8f113c2abcca77aa1ede7e2c36bb252e4f7b /test/-ext- | |
parent | 3cee99808d629c0ec493955ce8ea019d1f8a637b (diff) |
Tag string shared roots to fix use-after-free
The buffer deduplication codepath in rb_fstring can be used to free the buffer
of shared string roots, which leads to use-after-free.
Introudce a new flag to tag strings that at one point have been a shared root.
Check for it in rb_fstring to avoid freeing buffers that are shared by
multiple strings. This change is based on nobu's idea in [ruby-core:94838].
The included test case test for the sequence of calls to internal functions
that lead to this bug. See attached ticket for Ruby level repros.
[Bug #16151]
Notes
Notes:
Merged: https://github.com/ruby/ruby/pull/2480
Diffstat (limited to 'test/-ext-')
-rw-r--r-- | test/-ext-/string/test_fstring.rb | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/test/-ext-/string/test_fstring.rb b/test/-ext-/string/test_fstring.rb index 8612b5d710..9a54f6bfcc 100644 --- a/test/-ext-/string/test_fstring.rb +++ b/test/-ext-/string/test_fstring.rb @@ -71,4 +71,13 @@ class Test_String_Fstring < Test::Unit::TestCase str.freeze assert_fstring(str) {|s| assert_instance_of(S, s)} end + + def test_shared_string_safety + -('a' * 30).force_encoding(Encoding::ASCII) + str = ('a' * 30).force_encoding(Encoding::ASCII).taint + frozen_str = Bug::String.rb_str_new_frozen(str) + assert_fstring(frozen_str) {|s| assert_equal(str, s)} + GC.start + assert_equal('a' * 30, str, "[Bug #16151]") + end end |