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Description
Hi,
While fuzzing milkytracker with American Fuzzy Lop, I found a stack-based buffer overflow in LoaderXM::load(), in LoaderXM.cpp L646.
Attaching a reproducer (gzipped so GitHub accepts it): test02.xm.gz
Issue can be reproduced by running:
milkytracker test02.xm
=================================================================
==5561==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fff47f9e510 at pc 0x000000a23468 bp 0x7fff47f9e230 sp 0x7fff47f9e228
WRITE of size 4 at 0x7fff47f9e510 thread T0
#0 0xa23467 in LoaderXM::load(XMFileBase&, XModule*) /home/fcambus/milkytracker/src/milkyplay/LoaderXM.cpp:646:19
#1 0x95d324 in XModule::loadModule(XMFileBase&, bool) /home/fcambus/milkytracker/src/milkyplay/XModule.cpp:1976:40
#2 0x95cd03 in XModule::loadModule(char const*, bool) /home/fcambus/milkytracker/src/milkyplay/XModule.cpp:1954:22
#3 0x5b2849 in ModuleEditor::openSong(char const*, char const*) /home/fcambus/milkytracker/src/tracker/ModuleEditor.cpp:668:27
#4 0x7a7226 in Tracker::loadTypeFromFile(FileTypes, PPString const&, bool, bool, bool) /home/fcambus/milkytracker/src/tracker/Tracker.cpp:2694:43
#5 0x79f10f in Tracker::loadGenericFileType(PPString const&) /home/fcambus/milkytracker/src/tracker/Tracker.cpp:2570:11
#6 0x7978f8 in Tracker::handleEvent(PPObject*, PPEvent*) /home/fcambus/milkytracker/src/tracker/Tracker.cpp:533:3
#7 0xa8fdc3 in PPScreen::raiseEvent(PPEvent*) /home/fcambus/milkytracker/src/ppui/Screen.cpp:97:17
#8 0x815967 in RaiseEventSerialized(PPEvent*) /home/fcambus/milkytracker/src/tracker/sdl/SDL_Main.cpp:150:20
#9 0x81be7b in SendFile(char*) /home/fcambus/milkytracker/src/tracker/sdl/SDL_Main.cpp:872:2
#10 0x81c91a in main /home/fcambus/milkytracker/src/tracker/sdl/SDL_Main.cpp:974:3
#11 0x7f51856b0b6a in __libc_start_main /build/glibc-KRRWSm/glibc-2.29/csu/../csu/libc-start.c:308:16
#12 0x47b5f9 in _start (/home/fcambus/milkytracker/milkytracker+0x47b5f9)
Address 0x7fff47f9e510 is located in stack of thread T0 at offset 720 in frame
#0 0xa1a9bf in LoaderXM::load(XMFileBase&, XModule*) /home/fcambus/milkytracker/src/milkyplay/LoaderXM.cpp:64
This frame has 13 object(s):
[32, 262) 'insData' (line 65)
[336, 720) 'smpReloc' (line 66) <== Memory access at offset 720 overflows this variable
[784, 880) 'nbu' (line 67)
[912, 914) 'numSamples' (line 144)
[928, 1960) 'venv' (line 175)
[2096, 3128) 'penv' (line 176)
[3264, 3294) 'line' (line 265)
[3328, 3333) 'slot' (line 365)
[3360, 3389) 'buffer769' (line 481)
[3424, 4456) 'venv861' (line 538)
[4592, 5624) 'penv862' (line 539)
[5760, 5790) 'line1086' (line 631)
[5824, 5828) 'buffer1564' (line 832)
HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
(longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow /home/fcambus/milkytracker/src/milkyplay/LoaderXM.cpp:646:19 in LoaderXM::load(XMFileBase&, XModule*)
Shadow bytes around the buggy address:
0x100068febc50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x100068febc60: 00 00 00 00 00 00 00 00 06 f2 f2 f2 f2 f2 f2 f2
0x100068febc70: f2 f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x100068febc80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x100068febc90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x100068febca0: 00 00[f2]f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00
0x100068febcb0: 00 00 00 00 00 00 f2 f2 f2 f2 f8 f2 f8 f8 f8 f8
0x100068febcc0: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
0x100068febcd0: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
0x100068febce0: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
0x100068febcf0: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
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
==5561==ABORTING
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