diff options
| author | Bart Van Assche <bvanassche@acm.org> | 2020-05-18 21:07:37 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-05-19 09:40:29 -0600 |
| commit | cecbc9ce80e71a2894c7dfae6254b39cd4b8ba60 (patch) | |
| tree | 3e181e5cc37a5cab1123d0796820df9bdb83845f | |
| parent | 854b5f01dc6a7b59f0dddd646a80b1fcd767a8db (diff) | |
null_blk: Zero-initialize read buffers in non-memory-backed mode
This patch suppresses an uninteresting KMSAN complaint without affecting
performance of the null_blk driver if CONFIG_KMSAN is disabled.
Reported-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Alexander Potapenko <glider@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | drivers/block/null_blk_main.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c index 8efd8778e209..4f37b9fb28bb 100644 --- a/drivers/block/null_blk_main.c +++ b/drivers/block/null_blk_main.c @@ -1250,8 +1250,34 @@ static inline blk_status_t null_handle_memory_backed(struct nullb_cmd *cmd, return errno_to_blk_status(err); } +static void nullb_zero_read_cmd_buffer(struct nullb_cmd *cmd) +{ + struct nullb_device *dev = cmd->nq->dev; + struct bio *bio; + + if (dev->memory_backed) + return; + + if (dev->queue_mode == NULL_Q_BIO && bio_op(cmd->bio) == REQ_OP_READ) { + zero_fill_bio(cmd->bio); + } else if (req_op(cmd->rq) == REQ_OP_READ) { + __rq_for_each_bio(bio, cmd->rq) + zero_fill_bio(bio); + } +} + static inline void nullb_complete_cmd(struct nullb_cmd *cmd) { + /* + * Since root privileges are required to configure the null_blk + * driver, it is fine that this driver does not initialize the + * data buffers of read commands. Zero-initialize these buffers + * anyway if KMSAN is enabled to prevent that KMSAN complains + * about null_blk not initializing read data buffers. + */ + if (IS_ENABLED(CONFIG_KMSAN)) + nullb_zero_read_cmd_buffer(cmd); + /* Complete IO by inline, softirq or timer */ switch (cmd->nq->dev->irqmode) { case NULL_IRQ_SOFTIRQ: |