oss-fuzz: SEGV on unknown address 0x000000000000

reproduce with ./build-asan/tests/dav1d_fuzzer clusterfuzz-testcase-minimized-dav1d_fuzzer-56346149456445444

clusterfuzz-testcase-minimized-dav1d_fuzzer-5634614945644544

Error parsing frame header
ASAN:DEADLYSIGNAL
=================================================================
==16439==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f5a02177c2c bp 0x7ffd8a8
3e7d0 sp 0x7ffd8a83df38 T0)
==16439==The signal is caused by a READ memory access.
==16439==Hint: address points to the zero page.
    #0 0x7f5a02177c2b  (/lib64/libc.so.6+0xa8c2b)
    #1 0x7f5a02aba82e  (/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.0/libasan.so.4+0x7982e)
    #2 0x7f5a027ac202 in memcpy /usr/include/bits/string_fortified.h:34
    #3 0x7f5a027ac202 in backup_lpf ../src/lr_apply.c:73
    #4 0x7f5a027ad979 in dav1d_lr_copy_lpf_16bpc ../src/lr_apply.c:119
    #5 0x7f5a027c26fe in dav1d_filter_sbrow_16bpc ../src/recon.c:1465
    #6 0x7f5a02715cd6 in dav1d_decode_frame ../src/decode.c:2669
    #7 0x7f5a02719157 in dav1d_submit_frame ../src/decode.c:3036
    #8 0x7f5a026e48cd in dav1d_parse_obus ../src/obu.c:1088
    #9 0x7f5a027c42e7 in dav1d_decode ../src/lib.c:201
    #10 0x55faf65a8f6d in LLVMFuzzerTestOneInput ../tests/libfuzzer/dav1d_fuzzer.c:82
    #11 0x55faf65a873f in main ../tests/libfuzzer/main.c:87
    #12 0x7f5a020f0ae6 in __libc_start_main (/lib64/libc.so.6+0x21ae6)
    #13 0x55faf65a8969 in _start (/home/janne/src/dav1d/build-asan/tests/dav1d_fuzzer+0x1969)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/lib64/libc.so.6+0xa8c2b)
==16439==ABORTING