Heap buffer overflow (read) while loading map in CMapImages::LoadMapImages, mapimages.cpp:51

[mmmds]

The client crashes (only with ASAN) when an invalid map (9.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"
[...]
=================================================================
==33582==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61f0000dc28c at pc 0x5555556f4f08 bp 0x7ffffffd8cc0 sp 0x7ffffffd8cb0
READ of size 4 at 0x61f0000dc28c thread T0
    #0 0x5555556f4f07 in CMapImages::LoadMapImages(IMap*, CLayers*, int) /home/osboxes/teeworlds/teeworlds-asan/src/game/client/components/mapimages.cpp:51
    #1 0x555555839981 in CGameClient::OnConnected() /home/osboxes/teeworlds/teeworlds-asan/src/game/client/gameclient.cpp:459
    #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)

Address 0x61f0000dc28c is a wild pointer.
SUMMARY: AddressSanitizer: heap-buffer-overflow /home/osboxes/teeworlds/teeworlds-asan/src/game/client/components/mapimages.cpp:51 in CMapImages::LoadMapImages(IMap*, CLayers*, int)
Shadow bytes around the buggy address:
  0x0c3e80013800: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80013810: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80013820: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80013830: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80013840: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c3e80013850: fa[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80013860: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80013870: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80013880: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80013890: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e800138a0: 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
==33582==ABORTING

Doesn't crash without ASAN.