@leroysheep / BookAlchemy / commits / ae1ca21ac3

reftable/block: check deflateInit() return value

block_writer_init() allocates a z_stream and calls deflateInit() to prepare it for compressing log records. The return value of deflateInit() is silently discarded. If zlib initialization fails (e.g., Z_MEM_ERROR when the system is under memory pressure), the z_stream is left in an undefined state. Subsequent deflate() calls in block_writer_finish() then operate on this uninitialized stream. Depending on the zlib implementation, this can produce silently corrupted compressed data (which would be written to the reftable file and discovered only when a later reader fails to inflate) or crash outright. The function already uses REFTABLE_ZLIB_ERROR for deflate() failures later in the code path (lines 171, 199), so returning the same error code for deflateInit() failure is consistent. Pointed out by Coverity. Assisted-by: Claude Opus 4.6 Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Johannes Schindelin committed Jul 14, 2026 at 22:48 UTC ae1ca21ac306f855c0030ed660a39ead8a2af1e6

1 file changed +2 -1

reftable/block.c

+2 -1

index 920b3f4486..ec81fd0493 100644 --- a/reftable/block.c +++ b/reftable/block.c @@ -87,7 +87,8 @@ int block_writer_init(struct block_writer *bw, uint8_t typ, uint8_t *block, REFTABLE_CALLOC_ARRAY(bw->zstream, 1); if (!bw->zstream) return REFTABLE_OUT_OF_MEMORY_ERROR; - deflateInit(bw->zstream, 9); + if (deflateInit(bw->zstream, 9) != Z_OK) + return REFTABLE_ZLIB_ERROR; } return 0;