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Bug 4507

Summary: Heap buffer overflow in ConvertSint24ToSint32
Product: SDL Reporter: Geeknik Labs <geeknik>
Component: audioAssignee: Simon Hug <chli.hug>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: critical    
Priority: P2    
Version: 2.0.9   
Hardware: x86_64   
OS: Linux   
Attachments: POC

Description Geeknik Labs 2019-02-16 04:43:19 UTC 
Created attachment 3628 [details]
POC

The attached WAV file triggers a heap buffer overflow in SDL 2.0.9 using the fuzzing harness from https://www.ixiacom.com/company/blog/how-use-fuzzing-security-research.

==15811==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000000054 at pc 0x7efe72bc9cec bp 0x7ffed4e3b1b0 sp 0x7ffed4e3b1a8
READ of size 1 at 0x602000000054 thread T0
    #0 0x7efe72bc9ceb in ConvertSint24ToSint32 /root/SDL2-2.0.9/src/audio/SDL_wave.c:431:57
    #1 0x7efe72bc9ceb in SDL_LoadWAV_RW_REAL /root/SDL2-2.0.9/src/audio/SDL_wave.c:642
    #2 0x4f7c7d in main /root/tmp/harness_sdl.c:28:8
    #3 0x7efe719552e0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202e0)
    #4 0x41da49 in _start (/root/tmp/harness_sdl+0x41da49)

0x602000000054 is located 0 bytes to the right of 4-byte region [0x602000000050,0x602000000054)
allocated by thread T0 here:
    #0 0x4c91ff in realloc /b/swarming/w/ir/kitchen-workdir/src/third_party/llvm/compiler-rt/lib/asan/asan_malloc_linux.cc:165:3
    #1 0x7efe72cb46c0 in SDL_realloc_REAL /root/SDL2-2.0.9/src/stdlib/SDL_malloc.c:5359:11
    #2 0x7efe72bc91e9 in ConvertSint24ToSint32 /root/SDL2-2.0.9/src/audio/SDL_wave.c:414:28
    #3 0x7efe72bc91e9 in SDL_LoadWAV_RW_REAL /root/SDL2-2.0.9/src/audio/SDL_wave.c:642
    #4 0x4f7c7d in main /root/tmp/harness_sdl.c:28:8
Comment 1 Sam Lantinga 2019-06-10 15:59:39 UTC 
Simon, can you verify that your changes fix this issue?
Comment 2 Simon Hug 2019-06-10 21:02:27 UTC 
The WAVE file (attachment 3628 [details]) specifies a 1 byte block size for 24-bit PCM. data chunk is 5 bytes long.

With the current tip, SDL_LoadWAV_RW rejects this file with "Unsupported block alignment" as it expects a multiple of 3 for the block size (bits-per-samples * channels / 8).
Comment 3 Sam Lantinga 2019-06-11 13:26:17 UTC 
Great, thanks!