asan: flaky memory leak in cord_costart_thread_func

[avtikhon]

Tarantool version:
2.6.0-78-gc1f72aeb7
Target: Linux-x86_64-RelWithDebInfo
Build options: cmake . -DCMAKE_INSTALL_PREFIX=/usr/local -DENABLE_BACKTRACE=ON
Compiler: /usr/bin/clang-8 /usr/bin/clang++-8
C_FLAGS: -Wno-unknown-pragmas -fexceptions -funwind-tables -fno-omit-frame-pointer -fno-stack-protector -fno-common -msse2 -fsanitize=address -fsanitize-blacklist=/source/asan/asan.supp -std=c11 -Wall -Wextra -Wno-strict-aliasing -fsanitize=alignment,bool,bounds,builtin,enum,float-cast-overflow,float-divide-by-zero,function,integer-divide-by-zero,return,shift,unreachable,vla-bound -fno-sanitize-recover=alignment,bool,bounds,builtin,enum,float-cast-overflow,float-divide-by-zero,function,integer-divide-by-zero,return,shift,unreachable,vla-bound -Wno-char-subscripts -Wno-gnu-alignof-expression -Werror
CXX_FLAGS: -Wno-unknown-pragmas -fexceptions -funwind-tables -fno-omit-frame-pointer -fno-stack-protector -fno-common -msse2 -fsanitize=address -fsanitize-blacklist=/source/asan/asan.supp -std=c++11 -Wall -Wextra -Wno-strict-aliasing -fsanitize=alignment,bool,bounds,builtin,enum,float-cast-overflow,float-divide-by-zero,function,integer-divide-by-zero,return,shift,unreachable,vla-bound -fno-sanitize-recover=alignment,bool,bounds,builtin,enum,float-cast-overflow,float-divide-by-zero,function,integer-divide-by-zero,return,shift,unreachable,vla-bound -Wno-char-subscripts -Wno-invalid-offsetof -Wno-gnu-alignof-expression -Werror

OS version:
Debian GNU/Linux buster/sid

Bug description:
In asan/lsan check found memory leak:

Indirect leak of 32 byte(s) in 1 object(s) allocated from:
    #0 0x52501f in realloc (/tnt/src/tarantool+0x52501f)
    #1 0xf9bb06 in ev_realloc /source/third_party/libev/ev.c:1743:9
    #2 0xf9bb06 in array_realloc /source/third_party/libev/ev.c:1975
    #3 0xf9b98e in ev_feed_event /source/third_party/libev/ev.c:2024:7
    #4 0xfade70 in pipecb /source/third_party/libev/ev.c:2575:13
    #5 0xf9ff12 in ev_invoke_pending /source/third_party/libev/ev.c:3349:11
    #6 0xfa1ced in ev_run /source/third_party/libev/ev.c:3752:7
    #7 0x9da9e8 in cord_costart_thread_func /source/src/lib/core/fiber.c:1663:3
    #8 0x9d82c2 in cord_thread_func /source/src/lib/core/fiber.c:1463:14
    #9 0x7f387767dfa2 in start_thread (/lib/x86_64-linux-gnu/libpthread.so.0+0x7fa2)

Indirect leak of 32 byte(s) in 1 object(s) allocated from:
    #0 0x52501f in realloc (/tnt/src/tarantool+0x52501f)
    #1 0xf9bb06 in ev_realloc /source/third_party/libev/ev.c:1743:9
    #2 0xf9bb06 in array_realloc /source/third_party/libev/ev.c:1975
    #3 0xf9b98e in ev_feed_event /source/third_party/libev/ev.c:2024:7
    #4 0xfae984 in fd_event_nocheck /source/third_party/libev/ev.c:2069:9
    #5 0xfae984 in fd_event /source/third_party/libev/ev.c:2081
    #6 0xfae984 in epoll_poll /source/third_party/libev/ev_epoll.c:211
    #7 0xfa0a7a in ev_run /source/third_party/libev/ev.c:3718:9
    #8 0x9da9e8 in cord_costart_thread_func /source/src/lib/core/fiber.c:1663:3
    #9 0x9d82c2 in cord_thread_func /source/src/lib/core/fiber.c:1463:14
    #10 0x7f387767dfa2 in start_thread (/lib/x86_64-linux-gnu/libpthread.so.0+0x7fa2)

SUMMARY: AddressSanitizer: 64 byte(s) leaked in 2 allocation(s).

It was disabled in asan suppression file 'asan/lsan.supp' with block:

# test: vinyl/recover.test.lua
# source: src/lib/core/fiber.c
leak:cord_costart_thread_func

Steps to reproduce:
Login to dev1 test host

Start the docker container:

docker run --network=host -v $PWD:/source -w /source -ti registry.gitlab.com/tarantool/tarantool/testing/debian-buster:latest

Inside the docker container run:

mkdir /tnt ; cd /tnt/ ; rm -rf /tnt/*

CC=clang-8 CXX=clang++-8 cmake /source \
        -DCMAKE_BUILD_TYPE=RelWithDebInfo \
        -DENABLE_WERROR=ON \
        -DENABLE_ASAN=ON \
        -DENABLE_UB_SANITIZER=ON && make -j

cat >asan.patch <<EOF
diff --git a/asan/lsan.supp b/asan/lsan.supp
index 46b3001e9..6f0451d2e 100644
--- a/asan/lsan.supp
+++ b/asan/lsan.supp
@@ -58,4 +58,4 @@ leak:fiber_cxx_invoke
 
 # test: vinyl/recover.test.lua
 # source: src/lib/core/fiber.c
-leak:cord_costart_thread_func
+#leak:cord_costart_thread_func
EOF
patch -p1 -i asan.patch

cd test

Create test reproducer 'vinyl/gh-5324-recover.test.lua' based on 'vinyl/recover.test.lua':

box.cfg{}
s = box.schema.space.create('test', {engine = 'vinyl'})
_ = s:create_index('primary')
s:insert{1, 'test'}
box.snapshot()
os.exit()

And run command:

ASAN_OPTIONS=heap_profile=0:unmap_shadow_on_exit=1:detect_invalid_pointer_pairs=1:symbolize=1:detect_leaks=1:dump_instruction_bytes=1:print_suppressions=0 LSAN_OPTIONS=suppressions=/source/asan/lsan.supp /source/test/test-run.py --builddir /tnt --vardir /tnt/test/var --force vinyl/gh-5324-recover.test.lua

It will produce the issue.

Optional (but very desirable):

• coredump
• backtrace
• netstat