Reproduction:
export CFLAGS="-g -O0 -fsanitize=address,undefined" CXXFLAGS="-g -O0 -fsanitize=address,undefined"
export CC=afl-gcc CXX=afl-g++
./configure --disable-docs
make
make install
/usr/local/bin/sfconvert poc_file1 output format voc
poc_file1:
poc_file1.zip

Address Sanitizer result：
==2571893==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x7f3d05621800 at pc 0x7f3d0953be38 bp 0x7ffe6f6afca0 sp 0x7ffe6f6afc90
WRITE of size 2 at 0x7f3d05621800 thread T0
#0 0x7f3d0953be37 in ulaw2linear_buf /root/fuzz/fuzz_audiofile/audiofile/libaudiofile/modules/G711.cpp:42
#1 0x7f3d0953f15d in G711::runPull() /root/fuzz/fuzz_audiofile/audiofile/libaudiofile/modules/G711.cpp:206
#2 0x7f3d095006df in afReadFrames /root/fuzz/fuzz_audiofile/audiofile/libaudiofile/data.cpp:222
#3 0x55fcfd68faf4 in copyaudiodata /root/fuzz/fuzz_audiofile/audiofile/sfcommands/sfconvert.c:340
#4 0x55fcfd68f3de in main /root/fuzz/fuzz_audiofile/audiofile/sfcommands/sfconvert.c:248
#5 0x7f3d09029d8f (/lib/x86_64-linux-gnu/libc.so.6+0x29d8f)
#6 0x7f3d09029e3f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e3f)
#7 0x55fcfd68b784 in _start (/usr/local/bin/sfconvert+0x3784)

0x7f3d05621800 is located 0 bytes to the right of 12713984-byte region [0x7f3d04a01800,0x7f3d05621800)
allocated by thread T0 here:
#0 0x7f3d098b4887 in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:145
#1 0x55fcfd68f9e3 in copyaudiodata /root/fuzz/fuzz_audiofile/audiofile/sfcommands/sfconvert.c:327
#2 0x55fcfd68f3de in main /root/fuzz/fuzz_audiofile/audiofile/sfcommands/sfconvert.c:248
#3 0x7f3d09029d8f (/lib/x86_64-linux-gnu/libc.so.6+0x29d8f)

SUMMARY: AddressSanitizer: heap-buffer-overflow /root/fuzz/fuzz_audiofile/audiofile/libaudiofile/modules/G711.cpp:42 in ulaw2linear_buf
Shadow bytes around the buggy address:
0x0fe820abc2b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe820abc2c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe820abc2d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe820abc2e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe820abc2f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0fe820abc300:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe820abc310: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe820abc320: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe820abc330: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe820abc340: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe820abc350: 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
==2571893==ABORTING