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dm-integrity: don't modify bio's immutable bio_vec in integrity_metadata()

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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>
This commit is contained in:
Mikulas Patocka 2023-12-05 16:39:16 +01:00 committed by Greg Kroah-Hartman
parent 73bee12093
commit cb2b974ad5
1 changed files with 6 additions and 5 deletions
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11
drivers/md/dm-integrity.c
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@ -1257,11 +1257,12 @@ static void integrity_metadata(struct work_struct *w)
checksums = checksums_onstack;
__bio_for_each_segment(bv, bio, iter, dio->orig_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 {
@ -1270,7 +1271,7 @@ 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,
@ -1290,9 +1291,9 @@ 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;
}
}