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Commit 8e2a0361 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Greg Kroah-Hartman
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dm-integrity: don't modify bio's immutable bio_vec in integrity_metadata() 



commit b86f4b790c998afdbc88fe1aa55cfe89c4068726 upstream.

__bio_for_each_segment assumes that the first struct bio_vec argument
doesn't change - it calls "bio_advance_iter_single((bio), &(iter),
(bvl).bv_len)" to advance the iterator. Unfortunately, the dm-integrity
code changes the bio_vec with "bv.bv_len -= pos". When this code path
is taken, the iterator would be out of sync and dm-integrity would
report errors. This happens if the machine is out of memory and
"kmalloc" fails.

Fix this bug by making a copy of "bv" and changing the copy instead.

Fixes: 7eada909 ("dm: add integrity target")
Cc: stable@vger.kernel.org	# v4.12+
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 89b6ae90

drivers/md/dm-integrity.c

+6 −5
Original line number Diff line number Diff line
@@ -1379,11 +1379,12 @@ static void integrity_metadata(struct work_struct *w) 
			checksums = checksums_onstack;



		__bio_for_each_segment(bv, bio, iter, dio->bio_details.bi_iter) {

			struct bio_vec bv_copy = bv;

			unsigned pos;

			char *mem, *checksums_ptr;



again:

			mem = (char *)kmap_atomic(bv.bv_page) + bv.bv_offset;

			mem = (char *)kmap_atomic(bv_copy.bv_page) + bv_copy.bv_offset;

			pos = 0;

			checksums_ptr = checksums;

			do {
@@ -1392,7 +1393,7 @@ static void integrity_metadata(struct work_struct *w) 
				sectors_to_process -= ic->sectors_per_block;

				pos += ic->sectors_per_block << SECTOR_SHIFT;

				sector += ic->sectors_per_block;

			} while (pos < bv.bv_len && sectors_to_process && checksums != checksums_onstack);

			} while (pos < bv_copy.bv_len && sectors_to_process && checksums != checksums_onstack);

			kunmap_atomic(mem);



			r = dm_integrity_rw_tag(ic, checksums, &dio->metadata_block, &dio->metadata_offset,
@@ -1412,9 +1413,9 @@ static void integrity_metadata(struct work_struct *w) 
			if (!sectors_to_process)

				break;



			if (unlikely(pos < bv.bv_len)) {

				bv.bv_offset += pos;

				bv.bv_len -= pos;

			if (unlikely(pos < bv_copy.bv_len)) {

				bv_copy.bv_offset += pos;

				bv_copy.bv_len -= pos;

				goto again;

			}

		}