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Make decoder more fuzzer-friendly by disabling frame checks on fuzzing 

This commit disables CRC and zero-bit checking when
FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION is defined
This commit is contained in:
Martijn van Beurden 2022-01-14 14:41:13 +01:00 committed by Ralph Giles
parent b358381a10
commit 479f6038d9
1 changed files with 10 additions and 0 deletions
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10
src/libFLAC/stream_decoder.c
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@ -2081,7 +2081,11 @@ FLAC__bool read_frame_(FLAC__StreamDecoder *decoder, FLAC__bool *got_a_frame, FL
frame_crc = FLAC__bitreader_get_read_crc16(decoder->private_->input);
if(!FLAC__bitreader_read_raw_uint32(decoder->private_->input, &x, FLAC__FRAME_FOOTER_CRC_LEN))
return false; /* read_callback_ sets the state for us */
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
if(1){
#else
if(frame_crc == x) {
#endif
if(do_full_decode) {
/* Undo any special channel coding */
switch(decoder->private_->frame.header.channel_assignment) {
@ -2355,9 +2359,11 @@ FLAC__bool read_frame_header_(FLAC__StreamDecoder *decoder)
break;
}
#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
/* check to make sure that reserved bit is 0 */
if(raw_header[3] & 0x01) /* MAGIC NUMBER */
is_unparseable = true;
#endif
/* read the frame's starting sample number (or frame number as the case may be) */
if(
@ -2429,11 +2435,13 @@ FLAC__bool read_frame_header_(FLAC__StreamDecoder *decoder)
return false; /* read_callback_ sets the state for us */
crc8 = (FLAC__byte)x;
#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
if(FLAC__crc8(raw_header, raw_header_len) != crc8) {
send_error_to_client_(decoder, FLAC__STREAM_DECODER_ERROR_STATUS_BAD_HEADER);
decoder->protected_->state = FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC;
return true;
}
#endif
/* calculate the sample number from the frame number if needed */
decoder->private_->next_fixed_block_size = 0;
@ -2797,10 +2805,12 @@ FLAC__bool read_zero_padding_(FLAC__StreamDecoder *decoder)
FLAC__uint32 zero = 0;
if(!FLAC__bitreader_read_raw_uint32(decoder->private_->input, &zero, FLAC__bitreader_bits_left_for_byte_alignment(decoder->private_->input)))
return false; /* read_callback_ sets the state for us */
#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
if(zero != 0) {
send_error_to_client_(decoder, FLAC__STREAM_DECODER_ERROR_STATUS_LOST_SYNC);
decoder->protected_->state = FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC;
}
#endif
}
return true;
}