Heap use after free (read) while loading map in CDataFileReader::GetItem, datafile.cpp:406

[mmmds]

The client crashes (only with ASAN) when an invalid map (3.map.zip) is loaded. Such a map can be delivered to the client by a malicious server.

Tested on Ubuntu 20.04 x86_64, Teeworlds version: f35da54b6f2c5f9fd4bbd4559f887ccf8f8cc526

Compilation with ASAN:

export CXXFLAGS="-ggdb -O0 -fsanitize=address -fno-omit-frame-pointer"
export CFLAGS="-ggdb -O0 -fsanitize=address -fno-omit-frame-pointer"
cmake ..
make

Run and connect to a server that delivers an invalid map:

./teeworlds "connect 127.0.0.1" "gfx_fullscreen 0" "gfx_screen_height 240" "gfx_screen_width 360"
[...]
=================================================================
==31394==ERROR: AddressSanitizer: heap-use-after-free on address 0x61f00012e6e4 at pc 0x5555559764d5 bp 0x7ffffffd8c30 sp 0x7ffffffd8c20
READ of size 4 at 0x61f00012e6e4 thread T0
    #0 0x5555559764d4 in CDataFileReader::GetItem(int, int*, int*) /home/osboxes/teeworlds/teeworlds-asan/src/engine/shared/datafile.cpp:406
    #1 0x5555559764d4 in CDataFileReader::FindItem(int, int) /home/osboxes/teeworlds/teeworlds-asan/src/engine/shared/datafile.cpp:438
    #2 0x555555995f73 in CMap::Load(char const*, IStorage*) /home/osboxes/teeworlds/teeworlds-asan/src/engine/shared/map.cpp:37
    #3 0x5555555f0c6f in CClient::LoadMap(char const*, char const*, SHA256_DIGEST const*, unsigned int) /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:807
    #4 0x5555555f8408 in CClient::ProcessServerPacket(CNetChunk*) /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1251
    #5 0x5555555f997e in CClient::PumpNetwork() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1596
    #6 0x5555555f9d46 in CClient::Update() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1766
    #7 0x5555555fc9a0 in CClient::Run() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:2108
    #8 0x5555555d24e5 in main /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:2704
    #9 0x7ffff68e10b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #10 0x5555555dc48d in _start (/home/osboxes/teeworlds/teeworlds-asan/build/teeworlds+0x8848d)

0x61f00012e6e4 is located 2148 bytes inside of 3072-byte region [0x61f00012de80,0x61f00012ea80)
freed by thread T2 here:
    #0 0x7ffff76918df in operator delete(void*) (/lib/x86_64-linux-gnu/libasan.so.5+0x1108df)
    #1 0x7fffebe0f000  (/lib/x86_64-linux-gnu/libLLVM-10.so.1+0x1423000)

previously allocated by thread T2 here:
    #0 0x7ffff7690947 in operator new(unsigned long) (/lib/x86_64-linux-gnu/libasan.so.5+0x10f947)
    #1 0x7fffebe11b41  (/lib/x86_64-linux-gnu/libLLVM-10.so.1+0x1425b41)

Thread T2 created by T0 here:
    #0 0x7ffff75bb805 in pthread_create (/lib/x86_64-linux-gnu/libasan.so.5+0x3a805)
    #1 0x5555559cc6f6 in thread_init /home/osboxes/teeworlds/teeworlds-asan/src/base/system.c:484
    #2 0x5555555e224f in CGraphicsBackend_Threaded::StartProcessor(CGraphicsBackend_Threaded::ICommandProcessor*) /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/backend_sdl.cpp:56
    #3 0x5555555e224f in CGraphicsBackend_SDL_OpenGL::Init(char const*, int*, int*, int*, int*, int*, int, int, int*, int*) /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/backend_sdl.cpp:735
    #4 0x55555561719f in CGraphics_Threaded::IssueInit() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/graphics_threaded.cpp:753
    #5 0x555555617316 in CGraphics_Threaded::InitWindow() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/graphics_threaded.cpp:760
    #6 0x555555617dab in CGraphics_Threaded::Init() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/graphics_threaded.cpp:807
    #7 0x5555555fb64d in CClient::Run() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1951
    #8 0x5555555d24e5 in main /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:2704
    #9 0x7ffff68e10b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)

SUMMARY: AddressSanitizer: heap-use-after-free /home/osboxes/teeworlds/teeworlds-asan/src/engine/shared/datafile.cpp:406 in CDataFileReader::GetItem(int, int*, int*)
Shadow bytes around the buggy address:
  0x0c3e8001dc80: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c3e8001dc90: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c3e8001dca0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c3e8001dcb0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c3e8001dcc0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
=>0x0c3e8001dcd0: fd fd fd fd fd fd fd fd fd fd fd fd[fd]fd fd fd
  0x0c3e8001dce0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c3e8001dcf0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c3e8001dd00: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c3e8001dd10: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c3e8001dd20: 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
  Shadow gap:              cc
==31394==ABORTING

Doesn't crash without ASAN.