diff --git a/lib/zlib_dfltcc/dfltcc_deflate.c b/lib/zlib_dfltcc/dfltcc_deflate.c index 211d344710d5..d4c92f99808e 100644 --- a/lib/zlib_dfltcc/dfltcc_deflate.c +++ b/lib/zlib_dfltcc/dfltcc_deflate.c @@ -170,13 +170,18 @@ again: param->bcf = 0; dfltcc_state->block_threshold = strm->total_in + dfltcc_state->block_size; - if (strm->avail_out == 0) { - *result = need_more; - return 1; - } } } + /* No space for compressed data. If we proceed, dfltcc_cmpr() will return + * DFLTCC_CC_OP1_TOO_SHORT without buffering header bits, but we will still + * set BCF=1, which is wrong. Avoid complications and return early. + */ + if (strm->avail_out == 0) { + *result = need_more; + return 1; + } + /* The caller gave us too much data. Pass only one block worth of * uncompressed data to DFLTCC and mask the rest, so that on the next * iteration we start a new block.