tarantool / tarantool / 5888303428

86%

master: 88%

push

github

lua: fix heap-use-after-free bug in tuple format constructor

Runtime tuple formats are reusable, which means that a tuple format
returned by runtime_tuple_format_new may not be brand new, but actually
be used by a Lua object. As a result, if we call any function that may
trigger Lua GC between runtime_tuple_format_new and tuple_format_ref,
the tuple format may be deleted, leading to a use-after-free bug. This
is what happens in lbox_tuple_format_new. Fix this issue by taking a
reference to the format before pushing a cdata object to the Lua stack
in lbox_push_tuple_format.

The issue was fixed in the master branch by commit 28ec245d0a7e ("lua:
fix heap-use-after-free bug in tuple format constructor"). This isn't
a clean cherry-pick because the code changed quite a bit.

Closes #8889

NO_DOC=bug fix
NO_TEST=difficult to reproduce, found by ASAN

62345 of 114182 branches covered (54.6%)

1 of 1 new or added line in 1 file covered. (100.0%)

93353 of 108715 relevant lines covered (85.87%)

3164886.2 hits per line