4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx # v4.12+
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/dm-integrity.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -1379,11 +1379,12 @@ static void integrity_metadata(struct wo
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 @@ again:
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 @@ again:
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;
}
}
