Commit 4e870e94 authored Aug 30, 2016 by Mikulas Patocka Committed by Mike Snitzer Aug 30, 2016

dm crypt: fix error with too large bios



When dm-crypt processes writes, it allocates a new bio in
crypt_alloc_buffer().  The bio is allocated from a bio set and it can
have at most BIO_MAX_PAGES vector entries, however the incoming bio can be
larger (e.g. if it was allocated by bcache).  If the incoming bio is
larger, bio_alloc_bioset() fails and an error is returned.

To avoid the error, we test for a too large bio in the function
crypt_map() and use dm_accept_partial_bio() to split the bio.
dm_accept_partial_bio() trims the current bio to the desired size and
asks DM core to send another bio with the rest of the data.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # v3.16+

parent 91e630d9

drivers/md/dm-crypt.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -1924,6 +1924,13 @@ static int crypt_map(struct dm_target ti, struct bio bio)
		return DM_MAPIO_REMAPPED;
		}

		/*
		* Check if bio is too large, split as needed.
		*/
		if (unlikely(bio->bi_iter.bi_size > (BIO_MAX_PAGES << PAGE_SHIFT)) &&
		bio_data_dir(bio) == WRITE)
		dm_accept_partial_bio(bio, ((BIO_MAX_PAGES << PAGE_SHIFT) >> SECTOR_SHIFT));

		io = dm_per_bio_data(bio, cc->per_bio_data_size);
		crypt_io_init(io, cc, bio, dm_target_offset(ti, bio->bi_iter.bi_sector));
		io->ctx.req = (struct skcipher_request *)(io + 1);

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