Heap buffer overflow (read) while loading map in CLayers::InitTilemapSkip, layers.cpp:83

[mmmds]

The client crashes when an invalid map (7.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"
[...]
==33476==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61900082f94c at pc 0x5555559e6620 bp 0x7ffffffd8fa0 sp 0x7ffffffd8f90
READ of size 1 at 0x61900082f94c thread T0
    #0 0x5555559e661f in CLayers::InitTilemapSkip() /home/osboxes/teeworlds/teeworlds-asan/src/game/layers.cpp:83
    #1 0x5555558398d0 in CGameClient::OnConnected() /home/osboxes/teeworlds/teeworlds-asan/src/game/client/gameclient.cpp:454
    #2 0x5555555f6755 in CClient::ProcessServerPacket(CNetChunk*) /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1283
    #3 0x5555555f91ce in CClient::PumpNetwork() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1596
    #4 0x5555555f9596 in CClient::Update() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1766
    #5 0x5555555fc1f0 in CClient::Run() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:2108
    #6 0x5555555d24e5 in main /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:2704
    #7 0x7ffff68e10b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #8 0x5555555dc48d in _start (/home/osboxes/teeworlds/teeworlds-asan/build/teeworlds+0x8848d)

0x61900082f94c is located 0 bytes to the right of 972-byte region [0x61900082f580,0x61900082f94c)
allocated by thread T0 here:
    #0 0x7ffff768ebc8 in malloc (/lib/x86_64-linux-gnu/libasan.so.5+0x10dbc8)
    #1 0x555555973785 in CDataFileReader::GetDataImpl(int, int) /home/osboxes/teeworlds/teeworlds-asan/src/engine/shared/datafile.cpp:303
    #2 0x555555973785 in CDataFileReader::GetData(int) /home/osboxes/teeworlds/teeworlds-asan/src/engine/shared/datafile.cpp:341
    #3 0x5555559e6444 in CLayers::InitTilemapSkip() /home/osboxes/teeworlds/teeworlds-asan/src/game/layers.cpp:75
    #4 0x5555558398d0 in CGameClient::OnConnected() /home/osboxes/teeworlds/teeworlds-asan/src/game/client/gameclient.cpp:454
    #5 0x5555555f6755 in CClient::ProcessServerPacket(CNetChunk*) /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1283
    #6 0x5555555f91ce in CClient::PumpNetwork() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1596
    #7 0x5555555f9596 in CClient::Update() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1766
    #8 0x5555555fc1f0 in CClient::Run() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:2108
    #9 0x5555555d24e5 in main /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:2704
    #10 0x7ffff68e10b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)

SUMMARY: AddressSanitizer: heap-buffer-overflow /home/osboxes/teeworlds/teeworlds-asan/src/game/layers.cpp:83 in CLayers::InitTilemapSkip()
Shadow bytes around the buggy address:
  0x0c32800fded0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c32800fdee0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c32800fdef0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c32800fdf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c32800fdf10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c32800fdf20: 00 00 00 00 00 00 00 00 00[04]fa fa fa fa fa fa
  0x0c32800fdf30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c32800fdf40: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c32800fdf50: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c32800fdf60: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c32800fdf70: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
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
==33476==ABORTING

Compilation without ASAN:

export CXXFLAGS="-ggdb -O0"
export CFLAGS="-ggdb -O0"
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"
[...]
Segmentation fault (core dumped)