On Thu, Mar 21 2024 at 9:16P -0400,
Ming Lei <ming.lei@xxxxxxxxxx> wrote:
> For any bio with data, its start sector and size have to be aligned with
> the queue's logical block size.
>
> This rule is obvious, but there is still user which may send unaligned
> bio to block layer, and it is observed that dm-integrity can do that,
> and cause double free of driver's dma meta buffer.
>
> So failfast unaligned bio from submit_bio_noacct() for avoiding more
> troubles.
>
> Cc: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
> block/blk-core.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index a16b5abdbbf5..b1a10187ef74 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -729,6 +729,20 @@ void submit_bio_noacct_nocheck(struct bio *bio)
> __submit_bio_noacct(bio);
> }
>
> +static bool bio_check_alignment(struct bio *bio, struct request_queue *q)
> +{
> + unsigned int bs = q->limits.logical_block_size;
> + unsigned int size = bio->bi_iter.bi_size;
> +
> + if (size & (bs - 1))
> + return false;
> +
> + if (size && ((bio->bi_iter.bi_sector << SECTOR_SHIFT) & (bs - 1)))
> + return false;
> +
> + return true;
> +}
> +
> /**
> * submit_bio_noacct - re-submit a bio to the block device layer for I/O
> * @bio: The bio describing the location in memory and on the device.
> @@ -780,6 +794,9 @@ void submit_bio_noacct(struct bio *bio)
> }
> }
>
> + if (WARN_ON_ONCE(!bio_check_alignment(bio, q)))
> + goto end_io;
> +
> if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
> bio_clear_polled(bio);
>
> --
> 2.41.0
>
>
This check would really help more quickly find buggy code, but it
would be unfortunate for these extra checks to be required in
production. It feels like this is the type of check that should be
wrapped by a debug CONFIG option (so only debug kernels have it).
Do we already have an appropriate CONFIG option to use?
Mike
