[PATCH 5.4 47/84] dm-integrity: dont modify bios immutable bio_vec in integrity_metadata()

Greg Kroah-Hartman
2024-02-27T14:25:00Z

From: Mikulas Patocka <mpatocka@redhat.com>

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: 7eada909bfd7 ("dm: add integrity target")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/dm-integrity.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 81157801a3dc6..f3246f7407d61 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -1582,11 +1582,12 @@ static void integrity_metadata(struct work_struct *w)
}

__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 {
@@ -1595,7 +1596,7 @@ 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,
@@ -1615,9 +1616,9 @@ 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;
}
}
--
2.43.0