Heap buffer overflow (read) while loading map in CMap::Load, map.cpp:48

[mmmds]

The client crashes when an invalid map (4.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"
[...]
=================================================================
==31420==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61f0000e7d34 at pc 0x5555559965c5 bp 0x7ffffffd8c80 sp 0x7ffffffd8c70
READ of size 4 at 0x61f0000e7d34 thread T0
    #0 0x5555559965c4 in CMap::Load(char const*, IStorage*) /home/osboxes/teeworlds/teeworlds-asan/src/engine/shared/map.cpp:48
    #1 0x5555555f0c6f in CClient::LoadMap(char const*, char const*, SHA256_DIGEST const*, unsigned int) /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:807
    #2 0x5555555f8408 in CClient::ProcessServerPacket(CNetChunk*) /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1251
    #3 0x5555555f997e in CClient::PumpNetwork() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1596
    #4 0x5555555f9d46 in CClient::Update() /home/osboxes/teeworlds/teeworlds-asan/src/engine/client/client.cpp:1766
    #5 0x5555555fc9a0 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 0x61f0000e7d34 is a wild pointer.
SUMMARY: AddressSanitizer: heap-buffer-overflow /home/osboxes/teeworlds/teeworlds-asan/src/engine/shared/map.cpp:48 in CMap::Load(char const*, IStorage*)
Shadow bytes around the buggy address:
  0x0c3e80014f50: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80014f60: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80014f70: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80014f80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80014f90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c3e80014fa0: fa fa fa fa fa fa[fa]fa fa fa fa fa fa fa fa fa
  0x0c3e80014fb0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80014fc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c3e80014fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c3e80014fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c3e80014ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
==31420==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)