txn_box: Address use after free in Do_upstream_rsp_body

[bneradt]

ASan reported a use-after-free in Do_upstream_rsp_body. This adds clearing the Continuation's data of the State member upon destruction because any use of it will be a use after free by definition.

=================================================================
==764533==ERROR: AddressSanitizer: heap-use-after-free on address 0x62d006090610 at pc 0x7f5702f4d0d2 bp 0x7f5833a15ca0 sp 0x7f5833a15c90
READ of size 8 at 0x62d006090610 thread T24 ([ET_NET 22])
    #0 0x7f5702f4d0d1 in operator() /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/plugins/experimental/txn_box/plugin/src/Machinery.cc:2579
    #1 0x7f5702f4d0d1 in _FUN /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/plugins/experimental/txn_box/plugin/src/Machinery.cc:2591
    #2 0x1251b2a in INKContInternal::handle_event(int, void*) /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/src/api/InkContInternal.cc:153
    #3 0x116b304 in Continuation::handleEvent(int, void*) /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/include/iocore/eventsystem/Continuation.h:228
    #4 0x116b304 in Continuation::handleEvent(int, void*) /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/include/iocore/eventsystem/Continuation.h:224
    #5 0x116b304 in EThread::process_event(Event*, int) /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/src/iocore/eventsystem/UnixEThread.cc:162
    #6 0x116d132 in EThread::process_queue(Queue<Event, Event::Link_link>*, int*, int*) /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/src/iocore/eventsystem/UnixEThread.cc:197
    #7 0x116e07f in EThread::execute_regular() /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/src/iocore/eventsystem/UnixEThread.cc:255
    #8 0x116f7d8 in EThread::execute() /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/src/iocore/eventsystem/UnixEThread.cc:348
    #9 0x116f7d8 in EThread::execute() /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/src/iocore/eventsystem/UnixEThread.cc:326
    #10 0x11684e7 in spawn_thread_internal /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/src/iocore/eventsystem/Thread.cc:75
    #11 0x7f58493031c9 in start_thread (/lib64/libpthread.so.0+0x81c9) (BuildId: e08f397aa6b7de799209cd5bc35aabe0496678f1)
    #12 0x7f5848f6fe72 in __clone (/lib64/libc.so.6+0x39e72) (BuildId: 574d156ec0c828321a4038189fc1cfe74d0bb2ec)

0x62d006090610 is located 528 bytes inside of 32752-byte region [0x62d006090400,0x62d0060983f0)
freed by thread T24 ([ET_NET 22]) here:
    #0 0x7f584aa05170 in __interceptor_free.part.0 (/lib64/libasan.so.8+0xdc170) (BuildId: 71dbf393857c775be459ab5583ba7b5fcbd9c884)
    #1 0x7f5849b71665 in swoc::_1_5_12::MemArena::Block::operator delete(void*) _sdk/release_posix-x86_64_gcc_12/libswoc_1.5.12/include/swoc/MemArena.h:646
    #2 0x7f5849b71665 in swoc::_1_5_12::MemArena::~MemArena() _scm/libswoc/code/src/MemArena.cc:276

previously allocated by thread T24 ([ET_NET 22]) here:
    #0 0x7f584aa0662f in malloc (/lib64/libasan.so.8+0xdd62f) (BuildId: 71dbf393857c775be459ab5583ba7b5fcbd9c884)
    #1 0x7f5849b718ab in swoc::_1_5_12::MemArena::make_block(unsigned long) _scm/libswoc/code/src/MemArena.cc:99

Thread T24 ([ET_NET 22]) created by T0 ([TS_MAIN]) here:
    #0 0x7f584a971ea5 in __interceptor_pthread_create (/lib64/libasan.so.8+0x48ea5) (BuildId: 71dbf393857c775be459ab5583ba7b5fcbd9c884)
    #1 0x1168c0c in ink_thread_create /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/include/tscore/ink_thread.h:129
    #2 0x1168c0c in Thread::start(char const*, void*, unsigned long, std::function<void ()> const&) /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/src/iocore/eventsystem/Thread.cc:92
    #3 0x117a904 in EventProcessor::spawn_event_threads(int, int, unsigned long) /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/src/iocore/eventsystem/UnixEventProcessor.cc:467
    #4 0x117b75a in EventProcessor::start(int, unsigned long) /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/src/iocore/eventsystem/UnixEventProcessor.cc:548
    #5 0x56dc74 in main /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/src/traffic_server/traffic_server.cc:2104
    #6 0x7f5848f70d84 in __libc_start_main (/lib64/libc.so.6+0x3ad84) (BuildId: 574d156ec0c828321a4038189fc1cfe74d0bb2ec)

SUMMARY: AddressSanitizer: heap-use-after-free /sd/workspace/src/git.ouryahoo.com/Edge/build/_scm/trafficserver10.0_asan/plugins/experimental/txn_box/plugin/src/Machinery.cc:2579 in operator()
Shadow bytes around the buggy address:
  0x62d006090380: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x62d006090400: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x62d006090480: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x62d006090500: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x62d006090580: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
=>0x62d006090600: fd fd[fd]fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x62d006090680: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x62d006090700: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x62d006090780: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x62d006090800: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x62d006090880: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==764533==ABORTING

[brbzull0]

Seems reasonable to me. 🤞

[bneradt]

I verified in Yahoo production that this addresses the use after free.

[cmcfarlen]

Cherry-picked to v10.0.x